Henry IV, Holy Roman Emperor

Throne of Charlemagne in the Palatine Chapel in Aachen.

At the age of six, Henry succeeded his father unopposed.[29][30] Pope Victor II convinced the German aristocrats to swear fealty to their young king and enthroned him in Aachen.[30] He reminded them of their promise to consult Empress Agnes in case her son predeceased her and a successor had to be named.[31][32] Although she had been planning to enter a nunnery, Agnes was appointed her son's guardian.[29] She was responsible for her son's education along with a royal ministerialis (or unfree servant), Cuno.[33] She secured the most powerful aristocrats' support through lavish grants.[34] Agnes was reconciled with Godfrey the Bearded and made her late husband's other opponent, Conrad of the Ezzonen family, duke of Carinthia.[35]

Agnes took full control of state administration as regent after Pope Victor II left Germany early in 1057.[36] She paid little attention to Burgundy and Italy,[37] but he insisted on her royal prerogative to appoint bishops and abbots to the vacant German sees and monasteries.[38] Henry had inherited his father's Roman title of patrician, but the reformist concept of "liberty of the church" became dominant in Rome during his minority and his mother could not control papal elections.[12] Pope Victor's successor, Stephen IX—Godfrey the Bearded's brother—was elected without royal intervention early in August 1057, because the reformist clerics wanted to prevent their opponents from installing their own candidate as pope.[39]

A group of Saxon aristocrats plotted against Henry, fearing he would continue his father's oppressive policies after reaching the age of majority. They convinced Otto of Nordmark, who had recently returned from exile, to mount a coup. Henry's two relatives, Bruno II and Egbert I of Brunswick, attacked the conspirators. Bruno killed Otto but was mortally wounded in the skirmish.[40]

Agnes appointed a wealthy aristocrat, Rudolf of Rheinfelden, to be duke of Swabia in 1057.[34][41] She also charged him with the administration of Burgundy, likely because his extensive Burgundian domains enabled him to pacify the local nobles.[34][42] Godfrey the Bearded took possession of Spoleto and Fermo in the Papal States.[43] Rumours of Godfrey's determination to seize the imperial crown with Pope Stephen's help spread in Italy, but the Pope died unexpectedly on 29 March 1058.[43] The Roman aristocrats placed one of their number, Giovanni, Cardinal Bishop of Velletri, on the papal throne, however, the reformist clerics decided to elect Bishop Gerard of Florence pope.[12][43] They sent an envoy to Germany. Henry, "having deliberated with the princes" designated Gerard as the Pope in Augsburg on 7 June.[39]

King Andrew I of Hungary sent envoys to Germany in September 1058.[44] Emperor Henry III had launched two military campaigns against Hungary to enforce Andrew's oath of fealty; both campaigns ended in failure.[24] Now Andrew wanted to secure his five-year-old son Solomon's succession having earlier designated his brother, Béla, as his heir.[44] The Hungarian envoys and Henry's representatives concluded a peace treaty, and Henry's eleven-year-old sister, Judith, was engaged to Solomon.[39][44]

The reformist clerics elected Bishop Gerard pope in Florence in December 1058.[39] He took the name Nicholas II.[39][45] His advisor, the monk Hildebrand, was determined to strengthen the popes' autonomy.[46][47] The Pope held a synod which issued a decree establishing the cardinals' right to elect the popes.[48][49] Referring to Henry as "presently king and with the help of God emperor-to-be", the decree also confirmed the emperors' existing prerogatives over papal elections, but without specifying them.[50][51] A further decree prohibited lay investiture, but its scope was probably limited to lesser church offices because the European monarchs continued to appoint bishops without papal interference.[52][53] However, Cardinal Humbert of Silva Candida questioned the monarchs' right to invest clerics with bishoprics and abbeys in his treatises against simony already in 1057–1058.[54][55][56]

Henry jumps from Archbishop Anno II of Cologne's ship into the Rhine at Kaiserswerth in 1062 (engraving by Bernhard Rode, 1781).

Andrew I of Hungary faced his brother's rebellion in 1060.[57] Agnes dispatched Bavarian, Saxon and Bohemian troops to Hungary to fight Béla and his Polish allies, but the three armies did not coordinate their movements.[57] Béla defeated his brother who died of his wounds.[44][57] Andrew's family fled to Germany, and Béla was crowned king on 6 December.[44][57] After Béla's victory, the command of the German duchies along the Hungarian frontier had to be strengthened.[57] Agnes ceded Bavaria to a wealthy Saxon lord, Otto of Nordheim, and replaced Duke Conrad of Carinthia with Berthold of Zähringen in early 1061.[58]

Relations between Pope Nicholas and the German prelates became tense for unknown reasons in 1061.[59][60] A German synod sharply criticised the Pope and annulled his decrees.[60][61] When Nicholas died on 20 July 1061, the Roman aristocrats dispatched an embassy to Henry asking him to nominate a new pope.[49] Hildebrand and other reformist clerics elected Anselm of Baggio, Bishop of Lucca, pope on 30 September without Henry's confirmation.[60][62][63] Anselm took the name Pope Alexander II.[45][63] Henry summoned the Italian bishops to a synod in Basel to discuss the situation.[45][64] He attended the synod, wearing the insignia of his office of patrician of the Romans.[64] The synod elected Cadalus, Bishop of Parma antipope on 28 October.[64]

The election of two popes caused a schism that divided the German clergy. Some bishops supported Cadalus (now known as Honorius II), and others accepted Alexander II.[63] Archbishop Adalbert of Hamburg was Honorius's most prominent supporter, while Archbishop Anno II of Cologne acknowledged Alexander as the lawful pope.[63] Empress Agnes supported Honorius, for which her advisors were excommunicated by Alexander.[65] Her blatant favoritism for Bishop Henry II of Augsburg and the complete failure of the Hungarian campaign had compromised her prestige; the schism raised more indignation.[66][67] Archbishop Anno, Egbert of Brunswick, Otto of Nordheim and other discontented aristocrats decided to deprive her of the regency.[68] Archbishop Anno equipped a ship "with admirable workmanship" and sailed down the Rhine to an island near the royal palace at Kaiserswerth in April 1062.[66][69] The ship fascinated Henry, so Anno could easily talk him into a visit on it.[66] As soon as Henry stepped on board, the ship was cast off.[66] Fearing his captors wanted to murder him, Henry jumped into the river.[66][67] He almost drowned, but Egbert of Brunswick rescued him.[66]

The "Coup of Kaiserswerth" ruined the Empress's self-confidence, and she retired to her estates.[69][70] Anno replaced her as the head of the government. His new title of magister (or master) shows that he also took charge of Henry's education.[71] Anno appointed his kinsmen and his friends to the highest offices.[72] He persuaded Henry to cede one-ninth of the imperial income to him and his successors in Bremen.[73] Anno was determined to put an end to the schism.[33] In October 1062, the synod of the German bishops appointed his nephew, Burchard II, Bishop of Halberstadt, to begin negotiations with Pope Alexander II.[74] That same month, Peter Damian completed a treatise to defend the legality of Alexander II's election.[51] He emphasised that Henry's "right to participate in the papal elections ... is subject each time to reconfirmation by the pope".[51] Damian's argument implied that Henry only inherited a claim to the imperial prerogatives relating to papal elections, but he could forfeit it.[51] Respect for the monarch also declined in Germany.[75] The retainers of Abbot Widerad of Fulda and Bishop Hezilo of Hildesheim ignored Henry's commands when an armed conflict broke out between them in his presence at a church in Goslar in June 1063.[75][76]

Béla I of Hungary wanted to make peace with Henry to secure his throne against his nephew, Solomon, who had taken refuge in Germany.[77] Henry and his advisors, however, insisted on Solomon's restoration to the Hungarian throne and German troops invaded Hungary in August 1063.[77][78] Henry gained his first military experience during the campaign.[77][78] Béla died unexpectedly and the German army entered Székesfehérvár.[78] Henry installed Solomon on the throne and attended his wedding to Judith before returning to Germany.[77][79] Adalbert of Bremen accompanied Henry to the Hungarian campaign and struck up a friendship with him.[77] Adalbert was mentioned as Henry's "protector" in royal diplomas from 1063, showing his position was equal to Anno's.[77]

Anno went to Italy to attend a synod in Mantua in May 1064.[80] The synod recognised Alexander II as pope. He sent a legate to Germany to invite Henry to Rome.[81] Adalbert took advantage of Anno's absence to win more influence with Henry.[34][80]

Map of the Holy Roman Empire in the 10th and 11th centuries: Germany (blue), Italy (grey), Burgundy (orange to the West), Bohemia (orange to the East), Papal States (purple).

Henry was girded with a sword as a token of his coming of age in Worms on 29 March 1065.[82] According to the contemporaneous account of Lampert of Hersfeld, Henry attacked Archbishop Anno of Cologne soon after the ceremony and only his mother could calm him down.[83] Lampert's report is not fully reliable, but Anno was ousted from Henry's court.[84] At Worms, Henry accepted Pope Alexander II's invitation to Rome.[85] Agnes of Poitou recovered her influence, but she left Germany for Italy two months later.[86] After her departure, Archbishop Adalbert of Bremen took full control of state administration.[77] Henry's journey to Rome was postponed first until autumn, and then indefinitely, although the Pope needed Henry's presence to overcome his enemies.[34][87] Instead of travelling to Rome, Henry visited Burgundy in June 1065. Burgundian diplomas show the local aristocrats regarded his visit as the starting date of his reign in Burgundy. From Burgundy, Henry went to Lorraine where he granted Lower Lorraine to Godfrey the Bearded in October.[88][89]

Adalbert of Bremen, in concert with the King's young friend, Werner, seized Church property and took bribes for royal appointments. They persuaded the King to grant monasteries to the most powerful prelates and princes to appease their envy.[90] Adalbert also took advantage of his influence on Henry during his feud with the Saxon aristocrats. He denied to grant estates to Herman Billung, the brother of Ordulf, Duke of Saxony, and persuaded the King to heavily fine the Duke after Hermann launched a desperate raid against Bremen.[91] Adalbert's attempts to take possession of Lorsch Abbey by force caused his fall, because the scandal enabled Archbishops Siegfried of Mainz and Anno of Cologne to stage a plot.[92] They secured the support of Otto of Nordheim, Rudolf of Rheinfelden and Berthold of Zähringen and convinced Henry to dismiss Adalbert on 13 January 1066.[34][93] Anno regained the King's favour, but thereafter no royal advisors could take full control of state administration.[94]

Henry fell unexpectedly ill in the middle of May 1066. His sickness was so serious that he was thought to be dying. The aristocrats began to seek his successor, but he recovered in two weeks. He immediately married his bride, Bertha, most probably because the uncertainty about the childless monarch's succession caused widespread anxiety in his realms.[95][96] Prince Richard I of Capua who had acknowledged the Popes' suzerainty in 1059 rose up against Pope Alexander II and invaded the Papal States.[97] Early in 1067, Agnes of Poitou hurried back from Rome to Germany to persuade her son to intervene on the Pope's behalf. Henry ordered his troops to assemble at Augsburg in August, but Godfrey the Bearded was faster and launched a successful counter-offensive against Richard I in June. Godfrey's independent act was regarded as an insult to Henry's authority in Italy.[45][98] Adalbert of Bremen's fall had encouraged the Lutici (a pagan Slavic tribe dwelling over the river Elbe) to invade Germany and plunder Hamburg. In early 1069, Henry crossed the Elbe to punish the invaders and defeated them, but he could not prevent them from launching new plundering raids against Saxony.[99][100]

Large parcels of the royal demesne were distributed during Henry's minority, and he decided to recover them around 1069.[101] The bulk of the royal estates used to be in Saxony.[101] Henry sent Swabian ministeriales to the duchy to investigate property rights. The appointment of non-native unfree officials offended the Saxons, especially because the new officials ignored their traditional civil procedures.[101][102] New castles were built in Saxony and Henry manned them with Swabian soldiers.[101][103] Like his father, Henry spent more time in Saxony than in other parts of Germany and the accommodation of his retinue was the Saxons' irksome duty.[104] The Thuringians were also outraged that Henry supported Archbishop Siegfried of Mainz's claim to collect the tithes from them, although most Thuringians had been exempted of the Church tax for centuries.[105] The Margrave of Lower Lusatia, Dedi I, was the first Saxon lord to rebel.[105] He claimed benefices that his wife's former husband, Otto I, Margrave of Meissen, had held, but Henry refused him in 1069.[105][106] Dedi approached the Thuringians for help, but after Henry's promise to confirm their exemption from tithes the Thuringians joined the royal army. Henry invaded Dedi's domains and forced him to surrender.[105]

Otto of Nordheim held vast estates in Saxony.[101] After a nobleman, Egeno, accused him of plotting against Henry's life, Otto was summoned to "purge himself of that charge in single combat" early in August 1070. The contemporary historian, Bruno the Saxon, stated that Henry had hired Egeno against Otto, but his account is biased.[107] Fearing his case would not be judged fairly, Otto fled to Saxony.[101][108] He was soon outlawed and his benefices were confiscated.[107] Henry invaded Otto's Saxon domains, but Otto raided the royal estates in Thuringia.[107] Ordulf, Duke of Saxony, and most Saxon aristocrats remained loyal to Henry, but Ordulf's son and heir, Magnus, joined Otto's revolt.[109] Henry ceded Bavaria to Otto's wealthy son-in-law, Welf, at Christmas 1070.[106][110] Without their peers' support, Otto of Nordheim and Magnus of Saxony had to surrender. Henry placed them in the German princes' custody on 12 June 1071.[111]

When Archbishop Adalbert of Bremen died in early 1072, Henry seized his treasury—an early example of the application of the jus spolii by a German monarch.[112] Appointments to the highest Church offices were crucial elements of Henry's authority.[113] This practice enabled him to demand benefices for his supporters from the wealthy bishops and abbots, but the reformist clergy condemned it as simony.[113] When Henry appointed a Milanese nobleman, Gottfried, to the Archbishopric of Milan in 1070, Pope Alexander II excommunicated the new archbishop. Henry achieved Gottfried's consecration, however, which brought him into a prolonged conflict with the Holy See.[114][115][116] The Bishopric of Constance became another source of conflict in 1070 after the local clerics appealed to the Holy See to prevent the installation of Henry's candidate, Charles of Magdeburg, to the episcopal see.[117] Henry denied Charles had bribed him, but he publicly admitted at a synod that his advisors may have received money from Charles.[117] Charles had no choice but to resign to avoid the charge of simony.[117] The monks of the Reichenau Abbey also sought the Pope's support to prevent Henry from appointing an abbot to their monastery.[118] Pope Alexander I decided to investigate and summoned all German bishops who had been accused of simony or corruption to Rome.[113]

Henry's brother-in-law, King Solomon of Hungary, appeals to Henry for help (minitature in the 14th-century Vienna Illuminated Chronicle.)

Henry released Otto of Nordheim in May 1072, but Magnus of Saxony remained imprisoned.[101][119] The appointment of low-ranking men to royal offices outraged the German aristocrats.[120] Rudolf of Rheinfelden and Berthold of Zähringen left the royal court giving rise to rumours of an aristocratic plot.[120] Rudolf appealed to Agnes of Poitou, asking her to reconcile him with her son.[121] Agnes returned to Germany and mediated a reconciliation in July 1072. It proved temporary because Henry did not dismiss his advisors.[122] Rudolf and Berthold again withdrew to their duchies, and Welf of Bavaria also left the royal court.[123] Agnes of Poitou shared the dukes' negative views of Henry's advisors and persuaded Pope Alexander to excommunicate at least five of them in February 1073.[124][125] Henry however did not sever ties with his excommunicated advisors.[126]

Pope Alexander died and the Romans proclaimed Hildebrand as his successor on 22 April 1073.[124][125] Hildebrand, who assumed the name Gregory VII, did not seek confirmation from Henry although his election was not in line with the 1059 decree on papal elections.[115][124] He did not challenge Henry's prerogatives, but he was convinced a monarch who had regular contacts with excommunicated people could not intervene in Church affairs.[124][126] He regarded lay investiture as the principal barrier to completing the reform of the Church and challenged royal appointments, taking advantage of individual complaints against German prelates.[127] Henry's Italian chancellor, Bishop Gregory of Vercelli, and an assembly of the German bishops, urged the King to declare Gregory's election invalid. But the German dukes and Godfrey the Bearded's influential widow, Beatrice of Tuscany, convinced Henry that he should cooperate with the Pope.[128]

Bolesław II, Duke of Poland, invaded Bohemia in early 1073, and Henry therefore decided to launch a punitive action against him.[119] He ordered the Saxon aristocrats to assemble at Goslar on 29 June.[129] The Saxons refused to participate in the military campaign and asked Henry to redress their grievances, especially suggesting he stay in Saxony less often.[130][19] Henry withdrew from Goslar to Harzburg without making any concessions.[130] Otto of Nordheim soon convinced the assembled Saxons to take up arms for their liberties.[102][130] The Saxons marched to Harzburg, but Henry had fled to Eschwege.[130] The Thuringians and the Saxons concluded an alliance and captured Lüneburg.[131] To save the life of the commander of Lüneburg, Henry released Magnus of Saxony. The rebels acknowledged him as their lawful duke without seeking royal confirmation.[132] The German dukes and bishops did not come to Henry's rescue, and the rebels began attacking the royal castles in Saxony and Thuringia.[133] To prevent the rebellious Saxon bishops from securing the Pope's support, Henry addressed a letter of penance to the Pope, admitting he had been involved in simony.[134] He claimed his youthful arrogance had been responsible for his sins and blamed his advisors for his acts.[135]

Siegfried of Mainz, Anno of Cologne, Rudolf of Rheinfelden, Berthold of Zähringen and other German aristocrats came to Gerstungen to begin negotiations with the Saxon leaders in October 1073.[133] They tried to persuade Henry to redress the Saxons' grievances, but he was determined to crush the revolt.[133] A month later, Henry's servant, Regenger, informed Rudolf and Berthold that Henry was planning to murder them.[136] Regenger was ready to prove his words in a judicial duel, but he died unexpectedly in January 1074.[136] Henry, who had just recovered from an illness, moved to Worms.[136] The local bishop, Adalbert, denied his entry, but the townspeople rose up against the Bishop and surrendered Worms to Henry.[136][137] A grateful Henry exempted the burghers from customs duties, emphasising their loyalty in a time when "all the princes of the realm were raging" against him.[138]

Liemar, Archbishop of Bremen, Udo, Archbishop of Trier, and eight bishops came to visit Henry in Worms in early 1074.[136] Their retainers and the Worms militia joined Henry to a new military campaign against the Saxons and Thuringians.[139] The Thuringians had laid siege to Vokenroht (an unidentified royal fortress in Saxony) where Henry's pregnant wife was staying, but they allowed her to leave the fortress for Hersfeld Abbey.[139] Henry hurried to Hersfeld, but he soon realised the rebels outnumbered his army and entered into negotiations with them.[139] His troops were unwilling to fight, forcing Henry to accept the rebels' principal demands in the Treaty of Gerstungen on 2 February.[139] He agreed to destroy his castles and appoint only natives to offices in Saxony in return for the Saxon aristocrats' promise to raze their newly built fortresses.[140][141] On hearing the agreement, the Saxon peasants captured and destroyed Harzburg and desecrated the graves of Henry's younger brother and first-born son.[140][142] The destruction of the royal graves aroused public indignation, and Henry regarded it as a violation of the treaty.[106][143]

Ruins of Homburg Castle: Henry's army inflicted a decisive defeat on the Saxons near the castle in 1074.

Pope Gregory appointed the cardinal bishops Gerald of Ostia and Hubert of Palestrina to begin negotiations with Henry.[144] Agnes of Poitou accompanied the two legates to her son's court.[144] After Henry had done a public penance for simony, the legates absolved him on 27 April 1074.[145] They summoned the German bishops to a synod to hear the case of Bishop Herman I of Bamberg who had been accused of simony, but eight prelates did not obey their summons.[145] Henry did not intervene in the conflict, although the German prelates under investigation were his staunch supporters.[135]

Henry's brother-in-law, Solomon of Hungary, sent envoys to Henry seeking his assistance against his cousin Géza (who was Béla I of Hungary's eldest son).[146] Géza had defeated Solomon on 14 March 1074, forcing him to take refuge in the fortresses of Moson and Pressburg (now Mosonmagyaróvár in Hungary and Bratislava in Slovakia, respectively).[147] Solomon promised to cede six castles to Henry and acknowledge his suzerainty in return for Henry's support to recover his country.[147][148] Henry invaded Hungary and marched as far as Vác, but he could not force Géza into surrender.[149] Pope Gregory sharply criticised Solomon for his willingness to accept Henry's suzerainty, because the Pope regarded Hungary as a fief of the Holy See.[150]

On 7 December 1074, Pope Gregory asked Henry to compel the German prelates who had not obeyed his summons to attend a synod in Rome.[151] He also informed Henry of his new plan for a military expedition to Jerusalem to defend local Christians.[152] The Pope acknowledged Henry's role as the protector of the Holy See.[153] His plan to lead an armed pilgrimage, however, clearly ignored the secular rulers' so far widely acknowledged monopoly to take up arms in the defence of Christianity.[154] The Pope suspended five German bishops for disobedience at the synod of Lent in Rome in February 1075.[155] He also threatened Henry's five advisors with excommunication, blaming them for the conflict over the archbishopric of Milan.[155] Henry and the German bishops wanted to avoid a conflict, Archbishops Siegfied of Mainz and Liemar of Bremen travelled to Rome to begin negotiations with the Pope.[155] They acknowledged the Pope's decision about Bishop Herman of Bamberg's deposition, and the Pope charged Siegfried with holding a reforming synod in Germany.[155]

Henry had meanwhile make preparations to take vengeance of the desecration of royal graves at Harzburg. He promised amnesty and gifts to those who joined his campaign against Saxony.[106] Most German aristocrats and bishops hurried to Breitungen where the royal troops were assembling in June 1074.[156] Saxon nobles and prelates also deserted to the royal camp.[156] Under the command of Rudolf of Rheinfelden, the royal army launched a surprise attack on the Saxons at Homburg Castle on 9 June.[157] Most Saxon noblemen could flee from the battlefield, but many of the common foot soldiers were slaughtered.[158] Those who survived the massacre condemned the noblemen for their comrades' fate, and their stories turned the Saxon peasantry against their lords.[158] Pope Gregory VII congratulated Henry on his victory, stating that the Saxons' defeat at Homburg was an act of "divine judgement".[159] In his response, Henry asked the Pope to keep their correspondence secret because he thought that most German dukes were keen to maintain their conflict.[138][159]

Henry invaded Saxony again in autumn 1075.[160] Godfrey the Hunchback, Duke of Lower Lorraine, was the sole German duke to join his campaign, but the Saxons were unable to resist.[160] Otto of Nordheim convinced them to surrender unconditionally[140] to the King on 26 or 27 October.[160] Henry pardoned Otto and returned his benefices, except Bavaria, to him.[124] He showed no mercy to other rebel leaders[161] who were imprisoned and had their estates confiscated.[162] Henry summoned the German dukes to Goslar to swear fealty to his two-year-old son, Conrad, as his successor, but only Duke Vratislaus II of Bohemia obeyed his command.[163]

Henry begging Matilda of Tuscany and Hugh of Cluny in Canossa Castle (miniature in an illuminated manuscript kept in the Vatican Library, 1115).

Henry knew that his dependence on Pope Gregory VII weakened after his victory in the Saxon War.[159][164] He sent Count Eberhard the Bearded as his deputy to Italy.[165] Eberhard outlawed the supporters of the Pataria movement (or Patarini) and demanded an oath of fealty from the Pope's vassal, Robert Guiscard, Duke of Apulia and Calabria.[165][166] Henry made one of his chaplains, Tedald, archbishop of Milan contradicting the Pope's former decisions.[167] Alarmed by these acts, the Pope announced he would excommunicate Henry unless he changed his policies.[168]

Henry regarded the Pope's words as a clear denial of the sacred nature of kingship.[169] He held a synod in Worms on 24 January 1076.[170] Two archbishops, twenty-four German bishops (two-thirds of the German episcopate), one Burgundian bishop, an Italian bishop and Godfrey the Hunchback attended it.[171] At Henry's order, they declared the Pope's election invalid and demanded his abdication.[170][172] An assembly of the Lombardian bishops and aristocrats passed a similar resolution in Piacenza on 5 February.[173][174] Henry's most important ally, Godfrey the Hunchback, was murdered on 22 February.[174] Henry ignored Godfrey's last will and granted Lower Lorraine to his own son, Conrad.[175]

Pope Gregory VII was informed of the decisions of the two assemblies during the synod of Lent in Rome.[170] He excommunicated Henry and released his subjects from fealty in a public prayer addressed to Saint Peter.[170][173] The deposition of a monarch by a pope was unprecedented, but the Pope was convinced Henry's extraordinary arrogance could not be punished otherwise.[176] On learning of the Pope's decision Henry convoked a synod to Utrecht, but the local bishop, William I, was the only prelate willing to excommunicate the Pope.[177] Henry wanted to demonstrate that the Pope's denial of the monarchs' role in the administration of the Christian community was responsible for their conflict.[178] His chaplain, Gottschalk, completed a letter to be circulated in Germany, which emphasised that only God could judge a monarch.[179] The letter addressed the Pope as the "false monk, Hildebrand" and ended with the dramatic warning: "descend, descend!"[173] Two incidents occurred in succession which discouraged Henry's supporters: a fire after a lightning strike destroyed the cathedral of Utrecht on 27 March, and Bishop William's sudden death on 27 April.[179]

Henry's opponents regarded these incidents as divine retribution for his sinful acts.[164][179] Bishop Herman of Metz released the Saxon rebels who had been in his custody.[180] Bishop Burhard II of Halberstadt, who had been one of the leaders of the Saxon revolt, escaped from captivity and returned to Saxony.[180] Theoderic and William, members of the House of Wettin, also returned from exile and rose up against Henry.[180] Henry invaded Saxony in August, but only Vratislaus II of Bohemia accompanied him.[181] Their arrival provoked a general uprising, and Henry was forced to flee to Bohemia.[181] The German aristocrats and prelates met at Trebur from 16 October to 1 November.[181] They convinced Henry to accept the terms the Pope had set for him.[182] He had to promise to dismiss his excommunicated advisors and acknowledge Gregory as the lawful pope. Furthermore, he was to acknowledge the Pope's jurisdiction in his conflicts with the German dukes and bishops.[182] They announced they would elect a new king if Henry was unable to achieve his absolution before the anniversary of his excommunication.[183][184] They also invited Pope Gregory to Germany to hold an assembly in Augsburg on 2 February 1077.[184]

Henry moved to Speyer and lived there as a penitent.[185][186] He decided to depart for Italy to achieve his absolution, because he wanted to prevent the Pope from hearing his case at an assembly dominated by his enemies.[185] Although the winter was unexpectedly severe, Henry, his wife and their retainers crossed the Mont Cenis pass in December.[187] On 25 January, they reached Canossa Castle where the Pope had sought refuge, fearing that Henry came to Italy to capture him.[188] Henry was staying barefooted, wearing sackcloth at the castle for three days.[188] Matilda of Tuscany (who held the castle), Adelaide of Turin and Hugh of Cluny convinced the Pope he had no choice but to absolve the remorseful King.[188][189] Before receiving absolution, Henry had to pledge to accept the Pope's judgement in his conflict with his subjects.[190]

Henry remained in Italy after his absolution and issued charters of grants to his Italian supporters.[191] His absolution surprised his German opponents. They held an assembly at Forchheim, arguing that Henry's absolution had not restored their oaths of fealty.[192] The bishops, archbishops, dukes and the Saxons' representatives who attended the assembly elected Rudolf of Rheinfelden king on 14 March 1078.[193][194] Although the papal legates who were present acknowledged Rudolf's election, Pope Gregory VII remained neutral.[195] He maintained he was entitled to settle the dispute and informed both Henry and Rudolf he would hear their case at an assembly in Germany.[195]

On hearing of the election of an anti-king, Henry replaced Rudolf's principal ally, Berthold of Zähringen, with Liutold of Eppenstein as duke of Carinthia and awarded Sigehard, Patriarch of Aquilea, with Friuli.[196] He confiscated Swabia from Rudolf and Bavaria from Welf, placing both duchies under his direct control.[197] Before leaving Italy in April, Henry made his three-year-old son, Conrad, his lieutenant. He charged two excommunicated Italian prelates, Tedald of Milan and Denis of Piacenza, with Conrad's protection.[196] Unable to prevent Henry's return, Rudolf of Rheinfelden moved to Saxony.[198]

Henry visited Ulm, Worms, Nuremberg, Mainz, Strasbourg, Utrecht and Augsburg to demonstrate the full restoration of his royal authority.[199] He rewarded his supporters with estates confiscated from his opponents,[200] but in theory he could only make grants, because the grantees had to obtain their actual investment by force.[201] Henry and Rudolf's armies approached each other for the first time near Würzburg in August, but Henry avoided battle as his forces were outnumbered.[202] Both camps' aristocrats wanted to restore peace and agreed to hold a joint assembly in the absence of the kings at the Rhine in November. Henry used force to prevent them from beginning the negotiations.[203]

The papal legate, Cardinal Bernard, excommunicated Henry on 12 November 1077.[204][205] Henry sent Bishops Benno II of Osnabrück and Theoderic of Verdun to Rome to begin negotiations with the Pope whose position in Italy had been weakening.[206] He appointed a new legate who celebrated Easter with Henry in Cologne on 8 April 1078, demonstrating that the Pope had not regarded Henry's excommunication as valid.[206] Henry invaded Lotharingia and forced Bishop Herman of Metz into exile,[207] but Berthold of Zähringen and Welf of Bavaria inflicted defeats on his Swabian and Franconian supporters.[208] Rudolf of Rheinfelden hurried to Franconia and met Henry and his army of 12,000 Franconian peasants at Mellrichstadt on 7 August.[208] The Battle of Mellrichstadt proved indecisive, because both Rudolf and Henry were forced to flee from the battlefield.[209]

Rudolf of Rheinfelden dying after losing his right hand in the Battle on the Elster in 1080 (engraving by Bernhard Rode, 1781).

Pope Gregory prohibited all clerics from receiving royal appointments to bishoprics or abbeys in November 1078.[210][211] The papal decree not only threatened clerics who had received the royal investiture with excommunication, but it actually outlawed the practice.[211] The royal investiture was a basic element of royal administration. The ring and crosier the prelates received from monarchs during their installation symbolised their mutual dependence.[212] At the February 1079 synod of Lent, Henry's opponents, Bishops Altmann of Passau and Herman of Metz, convinced the Pope to send new legates to Germany, but the Pope forbade his legates to pass judgement against the prelates who had been appointed by Henry.[213]

Henry confiscated Rudolf of Rheinfelden's inherited Swabian estates and ceded them to Bishop Burchard of Lausanne in March.[214] In the same month, he made a wealthy local aristocrat, Frederick of Büren, duke of Swabia.[205][215] Frederick could only take possession of the lands north of the Danube, because Rudolf of Rheinfelden's son, Berthold, asserted his authority over the southern parts of Swabia.[216]

Henry met with the papal legates, Bishops Peter of Albano and Udalric of Padua, in Regensburg on 12 May 1079.[217] They convinced him to send envoys to Fritzlar to begin negotiations with Rudolf of Rheinfelden with their mediation.[217] At the Fritzlar conference, the parties agreed to hold a new meeting at Würzburg, but Rudolf failed to appoint his representatives thinking Henry had bribed the papal legates.[218] Henry invaded Saxony in August, but Rudolf persuaded the aristocrats in Henry's army to obtain his consent to a truce.[218] Henry sent agents to Saxony, and they convinced many Saxon leaders to desert the Anti-king.[218] He mustered troops from the German duchies, Burgundy and Bohemia and invaded Saxony in January 1080.[219] He could not surprise Rudolf who defeated Henry's army at Flarchheim on 27 January. Rudolf did not take advantage of his victory, however, because the Saxons who had deserted him did not return to his camp.[220]

Henry sent envoys to the synod of Lent in Rome and demanded the Pope excommunicate Rudolf hinting he was ready to appoint an antipope to achieve his goal.[212][221] On 7 March 1080, the synod issued a new decree prohibiting lay investiture and ordering the excommunication of the monarchs who had not abandoned this practice.[210][222] Pope Gregory excommunicated and deposed Henry and acknowledged Rudolf as the lawful king.[212][223] A treatise published in Henry's defence emphasised his hereditary claim to his realms. The treatise, known as The Defense of King Henry, uses arguments based on Roman Law, showing the Corpus Juris Civilis had already been studied in Italy. Before returning to Germany, Henry's envoys, Archbishop Liemar of Bremen and Bishop Rupert of Bamberg, raised a rebellion against the Pope's principal Italian ally Matilda of Tuscany. They also secured the support of Lombardian aristocrats for Henry.[224]

Henry's second excommunication was less harmful to his position than the previous ban.[187] He held a council in Mainz on 31 May 1080.[224] The nineteen German prelates and aristocrats who attended the council deposed Pope Gregory, labelling him as "the accused disturber of divine and human laws".[224] Henry held a second synod in Brixen. Italian, German and a lone Burgundian prelate confirmed the Pope's deposition 25 June, accusing him of simony, heresy and other sins.[212][225] The synod elected Archbishop Wibert of Ravenna pope.[226][227] Wibert assumed the name Clement III in reference to Pope Clement II who had been the first reformist pope to be elected through the intervention of Henry's father.[227] Henry returned to Germany and assembled his troops for a new invasion of Saxony.[228] Henry and Rudolf's armies met at Hohenmölsen on 14 October 1080.[228][229] Henry's forces were defeated but won the battle with a strategic outcome: Rudolf was mortally wounded losing his right hand and died.[229][230] Henry took full advantage of the circumstances of Rudolf's death, describing it as a punishment for oath-breaking.[226][231] He began negotiations with the Saxons, offering to appoint his son, Conrad, king of Saxony, but Otto of Nordheim persuaded his fellows to refuse the offer.[232]

Henry IV (left) and Antipope Clement III (middle-right) during Henry's imperial coronation (from Otto of Freising's Chronicle or History of the Two Cities, 1157).

Henry led a small army to Italy in March 1081.[233] His Lombardian supporters defeated Matilda of Tuscany's troops in the previous year, enabling him to reach Rome without resistance.[234] The Romans, however, remained loyal to Pope Gregory VII and Henry had to withdraw to northern Italy in late June.[235] He began negotiations with the envoys of the Byzantine Emperor Alexios I Komnenos about an alliance against Robert Guiscard.[236] He granted privileges to Lucca and Pisa, releasing them from Matilda's lordship.[237] While Henry was in Italy, the Saxons invaded Franconia.[238] Henry's southern German opponents elected Welf's kinsman, Hermann of Salm, king at a poorly attended assembly early in August. The Saxons only paid homage to Hermann four months later.[226][239]

Henry left Italy for Germany in the autumn of 1081 but returned in February 1082.[240] He laid siege to Rome but could not break the Romans' resistance.[241] He charged Antipope Clement with the siege of Rome and began devastating Matilda's domains.[242] Rumours of Hermann of Salm's plans to invade Italy forced Henry to remain in northern Italy, but Hermann did not risk an Italian campaign.[243] Henry returned to the siege of Rome at the end of 1082.[243] Emperor Alexios sent 144,000 gold pieces to him as a token of their friendship and promised a further 216,000 gold pieces in return for his support against Robert Guiscard.[244] The treasure enabled Henry to bribe Roman aristocrats, and his troops captured the Leonine City in Rome on 3 June 1083. Pope Gregory VII continued to resist in the Castel Sant'Angelo.[245][246] Henry withdrew from Rome again in early July. He concluded a secret treaty with the Roman aristocrats who promised to induce Gregory to crown Henry emperor or to elect another pope.[247]

Henry launched a military campaign against Robert Guiscard in February and March 1084.[248] During his absence, the Antipope convinced more than ten cardinals to desert Pope Gregory VII. They were followed by other clerics and papal officials.[249][250] Resistance against Henry collapsed, and he entered Rome on 21 March.[248][249] A synod condemned Gregory VII for high treason and deposed him, but he did not surrender.[251] Wibert was installed as pope and he crowned Henry emperor in St Peter's Basilica on 1 April.[246][252] Henry stayed in the Lateran Palace for six weeks. He left Rome before Robert Guiscard came to Gregory VII's rescue on 24 May.[253] Robert's troops destroyed Rome, outraging the Romans, and Gregory had to leave Rome for Salerno.[246][254] Henry ordered his Lombardian supporters to conquer Matilda of Tuscany's lands before he returned to Germany. However, her army routed his allies at the Battle of Sorbara on 2 July.[253]

Pope Gregory VII excommunicated Henry again in late 1084, but many of the Pope's former supporters came to pay homage to Henry as emperor at Cologne at Christmas.[255] His supporters and opponents held a joint conference on the river Werra on 20 January 1085 but could not reach a compromise.[256] The Saxon Count Theoderic II of Katlenburg and Bishop Udo of Hildesheim entered into secret negotiations with Henry during the conference. But the Saxons who remained hostile to Henry soon murdered Theoderic and forced the Bishop to flee from Saxony.[257] After the Bishop persuaded Henry to pledge he would respect the Saxons' liberties, many rebels laid down their arms.[258]

The papal legate, Cardinal Odo of Ostia, summoned the German prelates who were loyal to Pope Gregory VII to a synod at Quedlinburg.[259] The synod issued a decree that papal judgements could not be questioned and forbade the faithful to make contact with those who had been excommunicated.[259] In response, Henry held a general assembly in Mainz in late April or early May.[258][260] Three or four archbishops and fifteen bishops obeyed his summons. They deposed their peers—two archbishops and thirteen bishops—who had failed to come to Mainz.[258][41] The synod also established the "Peace of God" in Germany, prohibiting armed conflicts during the main Christian festivals.[260][261] Vratislaus II of Bohemia, who had always been Henry's loyal supporter, was rewarded with the title of king during the meeting.[262]

Henry visited Lower Lorraine to end a conflict between his two supporters, Bishops Theoderic of Verdun and Henry of Liège in June 1085.[263] He granted the County of Verdun to Henry of Liège's kinsman, Godfrey of Bouillon, and compensated Bishop Theoderic with estates confiscated from Matilda of Tuscany.[264] Peace was not restored, however, because Godfrey of Bouillon soon laid claim to Matilda's estates.[264] Henry invaded Saxony, reaching as far as Magdeburg in July.[265] Hermann of Salm, Hartwig, Archbishop of Magdeburg and the archbishop's three suffragans fled to Denmark and the Saxons paid homage to Henry.[265] Henry did not restore the rebels' confiscated estates and appointed new officials. The Saxons rose up in a new rebellion and forced Henry to withdraw to Franconia.[266] Henry mustered a new army and invaded Saxony in January 1086, but the Saxons avoided a pitched battle.[267] Henry withdrew to Regensburg. Welf of Bavaria laid siege to the town at Easter, but Henry was relieved by his supporters.[268]

Henry's Bavarian, Swabian and Saxon opponents laid siege to Würzburg in July 1086, because possession of the town could secure their uninterrupted communication.[268] Henry decided to force them to abandon the siege, but the rebels routed his army in the Battle of Pleichfeld on 11 August.[269] Before the battle the Swabian rebels, who regarded themselves as soldiers of a holy war, had brought a tall cross to the battlefield. Würzburg surrendered to the rebels, but they soon departed, enabling Henry to recapture the town.[270] Henry launched a military campaign against his enemies in Bavaria.[271] In an attempt to restore peace, Bavarian and Swabian aristocrats from both kings' camp held a joint conference in Oppenheim in February 1087. Henry did not attend.[271] He went to Aachen where his son, Conrad, was crowned his co-ruler on 30 May.[260][271] On this occasion Henry likely rewarded Godfrey of Bouillon with the Duchy of Lower Lorraine.[272]

A new joint conference of the German prelates and aristocrats assembled at Speyer in August 1087. Henry's opponents were willing to pay homage to him provided he had been absolved by the Pope. Henry refused them maintaining he had been unlawfully excommunicated. Pope Gregory VII's successor, Pope Victor III, held a synod in Benevento around the same time. The synod passed no resolution about Henry, suggesting the new Pope had adopted a conciliatory policy.[273] A sudden illness prevented Henry from invading Saxony in October. After his recovery he launched a military expedition against the Saxon rebels. One of the rebel leaders, Egbert II of Brunswick, began to negotiate his surrender. Henry offered him the Margravate of Meissen. This offer outraged Vratislaus of Bohemia who held Meissen. Egbert decided to continue the fight against Henry after two Saxon prelates, Hartwig of Magdeburg and Burchard of Halberstadt, promised the royal crown to him.[274] The two prelates could not keep their promises, and Egbert swore fealty to Henry in early 1088.[275] Egbert's about-face, and Burchard of Halberstadt unexpected death on 7 April 1088, accelerated the disintegration of the Saxon rebels' camp.[276][277] Hartwig of Magdeburg and his suffragans hurried to pay homage to Henry. Prominent Saxon aristocrats followed them to Henry's court.[277] He appointed Hartwig of Magdeburg to be his lieutenant in Saxony.[278]

Abandoned by his principal allies, Hermann of Salm sought Henry's permission to leave Saxony for Lorraine where he died on 28 September 1088.[276][278] Egbert of Brunswick rose up in a new rebellion and defeated Henry's army near Gleichen on 25 December.[279] Egbert's estates were confiscated in February 1089.[280] Henry, who had been widowed, went to Cologne to celebrate his marriage with Eupraxia of Kiev in the summer of 1089.[281] In the autumn, Henry returned to Saxony to prevent Egbert from attacking Hildesheim, but he continued to resist.[280]

Ruins of Canossa Castle: its defenders defeated Henry's troops in 1092.

Henry began negotiations with his Bavarian and Swabian opponents.[282] They were willing to surrender, but they demanded the deposition of Antipope Clement III.[282] Henry was inclined to accept their offer, but his bishops dissuaded him, fearing they would also be dismissed after the Antipope's fall.[282] To prevent further negotiations between the Emperor and his opponents, Pope Urban II mediated a marriage alliance between Welf of Bavaria's 18-year-old son, Welf the Fat and the 43-year-old Matilda of Tuscany in the autumn of 1089.[283][284] Henry decided to launch a new invasion of Italy.[285] The Jews of Speyer approached him around this time for the confirmation of their rights.[286] He summarised their liberties in a diploma, protecting them against physical assaults and prohibiting their forced baptism.[287] He issued a similar document for the Jews of Worms.[288] Henry was often in need of cash and according to Robinson, both communities had most probably paid a significant sum of money in return for his protection. [289]

Henry invaded Matilda's domains in March 1090, forcing her to seek refuge in the mountains in April.[285] The retainers of Henry's sister, Abbess Adelaide of Quedlinburg, killed Egbert of Brunswick on 3 July 1090.[249][290] Henry made Egbert's brother-in-law, Henry of Nordheim, his principal representative in Saxony.[290] Egbert's death put an end to Saxon opposition to the Emperor's rule, because he secured Nordheim's loyalty with frequent land grants.[249][291] Henry continued his Italian campaign and captured Matilda's fortresses north of the river Po at the end of 1091.[292] In June 1092, Henry crossed the Po and forced Matilda to begin negotiations for her surrender. But she and her vassals refused to acknowledge Clement III as the lawful pope.[293] Henry laid siege to Canossa, but the garrison made a surprise attack on his army, forcing him to abandon the siege in October.[294]

Henry's Swabian opponents elected the late Berthold of Rheinfelden's brother-in-law, Berthold II of Zähringen their duke and he proclaimed himself the "vassal of St Peter" (that is of the Holy See).[295] Henry had to send his German troops back to Germany to fight in Swabia and Bavaria.[296] He began negotiations with King Ladislaus I of Hungary about an alliance, but Welf I prevented their meeting.[296] Henry was forced to retreat to Pavia and Matilda's troops recaptured her fortresses.[297]

Henry and his two sons, Henry and Conrad (upper line) (from the 11th-century Evangelion of Saint Emmeram's Abbey).

Matilda of Tuscany and her husband managed to turn Henry's heir, Conrad, against him in the spring or summer of 1093.[284][296] Henry had Conrad captured, but he escaped to Milan.[297] According to Bernold of Constance, Henry tried to commit suicide after his son's rebellion.[298] Bernold likely invented this story to make a comparison between Henry and King Saul.[299] Conrad's disloyalty aroused Henry's suspicion of his relatives, and he put his wife under strict supervision, allegedly for her infidelity.[298][300] Four Lombardian towns (Milan, Cremona, Lodi and Piacenza) made an alliance with Matilda of Tuscany.[297] Henry fled to Verona because its margrave, Henry of Eppenstein, and Eppenstein's brother, Patriarch Udalric of Aquileia, remained his last supporters in Italy.[301] Henry's authority remained limited to northeastern Italy, and Matilda and Welf I's troops prevented his return to Germany.[302][303]

Empress Eupraxia decided to desert Henry and sought Matilda's assistance to rescue her from her house arrest early in 1094. Matilda sent a small force of soldiers to Verona who liberated the Empress and accompanied her to Tuscany.[304] Once meeting with Matilda, Eupraxia presented serious charges against her husband, accusing him of debauchery and group rape. She publicly repeated the her charges in Pope Urban II's presence at the Council of Piacenza in March 1095.[305][306] The Pope endorsed her words and confirmed Conrad's claim to the throne, recognizing him as the lawful king in April.[298] Henry's enemies gladly spread Eupraxia's accusations—modern scholars, however, have regarded her statements as an effective propaganda tool against Henry, likely fabricated by Matilda's advisors.[303] The Pope departed from Piacenza to France in triumph, but the teenage Welf the Fat left his middle-aged wife around the same time.[307] The separation of Matilda and her husband came as a severe blow to the Pope, because the young Welf's father, Welf I, soon sought a reconciliation with Henry.[284][308][309] Henry also conducted negotiations with Doge Vitale Faliero in Venice in June 1095. They renewed a commercial treaty and Faliero agreed to continue to pay a yearly tribute to the Emperor.[310]

Pope Urban II proclaimed the First Crusade at the Council of Clermont in November 1095.[311][312] The council also prohibited the bishops and abbots from swearing fealty to secular rulers.[313] The first crusader bands, composed mainly of commoners and impoverished knights, departed for the Holy Land early in 1096.[314] They attacked the towns along the Rhine and massacred thousands of Jews.[314][315] After the first pogroms, the Jews sent a letter to Henry, seeking his protection.[289] Henry ordered the German bishops, dukes and counts to protect the Jewish communities, but they could rarely prevent the fanatical mob from persecuting them.[289][316]

Welf of Bavaria's father, Adalbert Azzo II of Este, mediated a reconciliation between his son and the Emperor in early 1096.[309] Henry restored Bavaria to Welf who lifted the blockade of the Alpine passes enabling Henry to return to Germany in May.[317][318] Aristocrats who had rebelled against Henry came to pay homage to him at assemblies held in Regensburg, Nuremberg and Mainz.[319] He allowed the Jews, who had been forcibly converted to Christianity, to return to Judaism.[316][320] In early 1098, Berthold II of Zähringen was also reconciled with Henry who exempted his domains from the jurisdiction of the dukes of Swabia and rewarded him with the hereditary title of duke.[319][321]

The German magnates and prelates deposed Henry's rebellious son, Conrad, and elected his 12-year-old brother, Henry V, as Henry's co-ruler in May 1098.[322][323] The younger Henry had to pledge he would always submit to his father's authority.[324] While in Mainz Henry ordered an investigation into the missing property of the Jews who had been murdered by the crusaders.[320] Several witnesses stated that Archbishop Ruthard of Mainz and his kinsmen had stolen large portions of it.[320] Fearing retribution, the Archbishop and his kinsmen fled to Thuringia and began plotting against Henry.[316][320]

Mikveh (Jewish ritual bath) in Speyer: Henry summarised the local Jews' liberties in a diploma in 1090.

Bretislav II, Duke of Bohemia, met Henry in Regensburg at Eastertide 1099. He wanted to alter the traditional order of succession to the Bohemian throne in favour of his brother, Bořivoj II.[325] Henry granted his request and invested Bořivoj with Bohemia on 19 April. Although the dukes of Bohemia had acknowledged the German monarchs' suzerainty, this was the first occasion that a Bohemian duke was invested in the same manner as the rulers of the German duchies.[326] The restoration of public order was one of Henry's principal goals during the next months.[327] He held assemblies at Bamberg and Mainz and ordered the (mainly Franconian and Saxon) magnates who were present to pursue robbers and thieves.[327]

Antipope Clement III died on 8 September 1100, and his cardinals elected Theoderic of Albano as his successor.[328][329] Henry's Italian supporters acknowledged Theoderic as the lawful pope, but Henry did not make contact with him.[322][327] Count Henry of Limburg captured properties of the Prüm Abbey.[330] The Emperor laid siege to Limburg, forcing the Count to surrender in May 1101.[331] The Emperor soon forgave Henry of Limburg for his rebellion and made him duke of Lower Lorraine before the end of the year.[331]

An assembly of the German leaders proposed that Henry make peace with Pope Urban II's successor, Paschal II in late 1101; there is no proof Henry followed their advice.[332] Pope Paschal II was determined to overcome Henry and ordered his legate, Bishop Gehard of Constance, to keep the resistance against the Emperor alive in Germany.[332] The papal synod repeated the ban on lay investiture and the bishops' oath of fealty to secular rulers early in 1102.[333] The synod also confirmed Henry's excommunication in the Lateran Basilica on 3 April.[322][334]

Robert II, Count of Flanders allied with Bishop Manasses of Cambrai against Walcher whom Henry had appointed as bishop of Cambrai.[335] Robert laid siege to Cambrai. Henry came to Walcher's rescue forcing Robert to lift the siege in October 1102.[335] Robert resumed the war on Walcher soon after Henry left Cambrai.[336] Henry held a general assembly in Mainz on 6 January 1103.[334] He proclaimed the Landfrieden (or imperial peace), prohibiting feuds and other acts of violence for the first time in the whole empire.[322][328] He threatened those who broke the peace with mutilation, without allowing the wealthy to pay penance.[328]

Henry also announced he was planning to launch a crusade to the Holy Land.[328] He addressed a letter to Hugh of Cluny. In it he explained to his godfather he intended to "make good the ruin of the Church, which was caused by us, through the restoration of peace and justice".[337] His correspondence with Hugh (who was Pope Paschal II's staunch supporter) suggests Henry was seeking reconciliation.[338] The Pope regarded Henry as the "chief of the heretics". He granted Robert II of Flanders the crusaders' spiritual privileges for their fight against the Emperor's supporters, promising the "remission of sins" to them.[334][339] Robert II, however, feared losing his imperial fiefs and swore fealty to Henry in Liège on 29 June 1103.[336]

Henry IV abdicates in favour of Henry V (from the early-12th-century Chronicle of Ekkehard von Aura).

Henry V visiting his father in prison

A Bavarian count, Sigehard of Burghausen, criticised Henry for his favouritism towards the Saxon and Franconian aristocrats in Regensburg in January 1104.[340] He had come to Regensburg accompanied by a large retinue arousing Henry's suspicion he was staging a plot.[340] After Sigehard dismissed his retainers, a band of ministeriales and burghers murdered him on 4 February.[341][342] The ministeriales likely took revenge on Sigehard for his arbitration in a case relating to their peers. Sigehard's kinsmen and other aristocrats, however, blamed Henry for his death saying he had failed to defend him.[322][343]

Archbishop Hartwig of Magdeburg died in autumn 1104.[344] His brother, Burgrave Herman of Magdeburg, and their nephew, Hartwig, departed for Henry's court most probably to achieve the younger Hartwig's appointment to the archbishopric. But Count Theoderic III of Katlenburg captured and imprisoned them for simony.[344] Henry launched a punitive campaign against Theoderic.[344] The military expedition ended abruptly because Henry's eighteen-year-old son unexpectedly deserted him and fled to Bavaria on 12 December.[344] Later, the younger Henry stated that his father's failure to receive an absolution from the Pope had prompted his rebellion. His nearly contemporaneous biography claims that he wanted to secure the aristocrats' support before his ailing father's death to avoid a succession crisis.[345][346] The discontented Bavarian aristocrats hurried to the young King and Pope Paschal II absolved him from excommunication early in 1105.[318][347] Henry sent envoys to his son, but he refused to negotiate with an excommunicated man.[347]

Most Swabian and eastern Franconian aristocrats joined the younger Henry's rebellion. He also secured the Saxons' support during a visit in Saxony in April 1105.[348] He launched a military campaign against Mainz to restore Archbishop Ruthard to his see in late June 1105, but his father's supporters prevented him crossing the Rhine.[349] Henry expelled his son's troops from Würzburg in August, but his authority was quickly waning.[350] His son took advantage of Frederick of Büren's death to take control of Swabia.[350] Leopold III, Margrave of Austria, and Bořivoj II, Duke of Bohemia, deserted the Emperor at Regensburg in late September; Bořivoj soon repented his betrayal.[351] He supported Henry's flight from Regensburg to Saxony. His brother-in-law, Count Wiprecht of Groitzsch, accompanied Henry as far as Mainz in late October.[352] Already exhausted, Henry sent a letter to his son, asking him "not to persist in his desire to depose him from the kingship"; the younger Henry wanted no compromise.[353]

Henry moved from Mainz to Hammerstein and then to Cologne. He decided to return to Mainz, because he wanted to defend himself at the German princes' assembly his son had convoked.[353] The younger Henry met with his father at Koblenz on 21 December. Henry dismissed his retinue, because his son promised a safe conduct to Mainz.[354] Instead, he was captured and brought to the castle of Böckelheim [355][356] where he was also forced to cede the royal insignia to his son.[354] The burghers of Mainz remained loyal to Henry so his son summoned the German princes' to an assembly at Ingelheim.[355] Henry was allowed to attend the meeting, but it was dominated by his enemies.[355] Having no other choice, he abdicated in his son's favour on 31 December.[357] Later, he said he resigned only because of his "fears of imminent murder or execution".[358]