Ulrich III, Duke of Carinthia

Ulrich III was the eldest son of Duke Bernhard of Carinthia and his wife Judith, a daughter of the Přemyslid king Ottokar I of Bohemia.[1] Already his father had endeavoured to assume the rule over the Carniolan march, which Ulrich could secure for himself by marrying Agnes of Andechs, the widow of the last Babenberg duke Frederick II of Austria.[1] From 1251, he was co-ruler of Carinthia with his father; in 1256 he succeeded his father as duke.[1]

Later version Ulrich's seal, which became the Carinthian coat of arms

Ulrich continued the development of his home territories as his father began. In 1260, he completed the foundation of the charterhouse in Bistra (Freudenthal) in Inner Carniola.[1] He also founded the Canons Regular monastery in Völkermarkt.[1]

He had differences of opinion about his father's inheritance with his younger brother Philip, who had to prepare for an ecclesiastical career and was elected Archbishop of Salzburg in 1247. Philip refused to take holy orders in order to reserve the right of succession in Carinthia for himself. Ulrich and Philip finally reached an agreement of mutual protection and inheritance and, after Philip was deposed as bishop in 1257 by the cathedral chapter, fought together against Philip's successor, Archbishop Ulrich of Seckau.

After the election of Archbishop Ladislaus of Salzburg, it became clear that Philip would have to abandon all hopes to return to Salzburg. In 1267 he asked Ulrich III to divide their inheritance and also proposed that he could be Ulrich's heir, as Ulrich's son from his first marriage had died young, and his second marriage was still childless. However, on 4 December 1268, Ulrich secretly proceeded to Poděbrady Castle, where he concluded an inheritance treaty with his cousin, King Ottokar II of Bohemia,[1] in which the king was made his sole heir.

When Duke Ulrich III died in Cividale del Friuli on 27 October 1269, both Philip and Ottokar II claimed his inheritance. In the same year, Philip was elected Patriarch of Aquileia, however, his election was never confirmed by the Pope and in 1270/71 he was expelled to Austria by Ottokar's forces. This was the end of the 150-year long rule of the Sponheim dynasty in Carinthia.

Ulrich III was married twice:

1. to Agnes of Merania (1215–1263), the widow of Duke Frederick II of Austria.[1] This marriage produced a son, who died young.
2. to Agnes of Baden (1250–1295), a daughter of Margrave Herman VI of Baden and Gertrude of Babenberg,[1] niece of Duke Frederick II of Austria. This marriage remained childless.

• Franz von Krones (1895), "Ulrich III. (Herzog von Kärnten)", Allgemeine Deutsche Biographie (ADB) (in German), 39, Leipzig: Duncker & Humblot, pp. 222–225
• Friedrich Hausmann: Die Grafen zu Ortenburg und ihre Vorfahren im Mannesstamm, die Spanheimer in Kärnten, Sachsen und Bayern, sowie deren Nebenlinien, in the series Ostbairische Grenzmarken — Passauer Jahrbuch für Geschichte Kunst und Volkskunde, vol. 36, Passau, 1994
• Dr. Eberhard Graf zu Ortenburg-Tambach: Geschichte des reichsständischen, herzoglichen und gräflichen Gesamthauses Ortenburg, part 1: Das herzogliche Haus in Kärnten, Vilshofen, 1932

• Ulrich III in the thesaurus maintained by the Consortium of European Research Libraries