New Fourth Army

In 1938 the 1st, 2nd and 3rd detachments began marching to the battlefront in southern Anhui and southern Jiangsu. The 4th detachment got northern and middle Anhui . Because they were in the back of the Japanese army, the New Fourth Army didn't annihilate too much Japanese troops at first. In most of the time they were establishing base areas and recruiting new recruits. After the Japanese had occupied Wuhan, the New Fourth Army took the opportunity to set up several guerrilla camps in this area.

In 1939, the Japanese Army stopped attacking the Nationalist forces on a large scale. The New Fourth Army was restricted in the south of the Yangtze River. In order to establish a new base area, the New Fourth Army sent an advance team to Northern Jiangsu and conflicted with guerrillas of the Nationalist forces here. In the battle of Huangqiao, the New Fourth Army destroyed the 89th Army and the 33rd division of the Nationalist forces. The Eighth Route Army also dispatched the 4th detachment's 12,000 men to support the New Fourth Army.

In January 1941 the Nationalist forces surrounded and destroyed the headquarters of the New Fourth Army in retaliation. The New Fourth Army lost about 8,000 soldiers. The commander of the New Fourth Army was also caught. The Communist Party of China (CCP) made a strong protest and announced the rebuilding the New Fourth Army in northern Jiangsu. At this time the New Fourth Army had already seven divisions and 90,000 soldiers. Between 1941 and 1943, the New Fourth Army fought mainly with the Japanese and lost a part of base areas. Because of the heavy losses, the 6th Division's designation was revoked.

Because of the lack of troops, the Japanese ceased attacking the New Fourth Army actively. Several fierce battles erupted again between the New Fourth Army and the Nationalist forces. The New Fourth Army tried to establish base areas in eastern Zhejiang, Hunan and Hubei Province. When World War Two ended, they stopped operations and withdrew from base areas. At this time, the New Fourth Army already had 268,000 soldiers. In order to occupy northeast China in time, Huang Kecheng ordered the 3rd Division's 35,000 men to leave his base area.

In summer 1946, Chinese Civil War had broke out. The Nationalist forces attacked the 5th Division first and occupy its base area successfully. But in middle Jiangsu Su Yu's 1st Division miraculously won by fewer and wiped out 56,000 soldiers of the Nationalist forces. Because of the lack of troops, the 1st Division, 2nd Division, 4th Division and 7th Division had to withdraw to Shandong in winter 1946. In January 1947, the New Fourth Army and Shandong Military Region of People's Liberation Army were merged into East China Field Army.

Most of New Fourth Army's military officers were the guerrillas of Chinese Red Army, the others were from 8th Route Army . The experience in China's Civil War made them rapidly expand their forces in the beginning of the Second Sino-Japanese War . During the eight years of the war the officers with excellent abilities were usually promoted faster . For example, general Zhang Aiping was only a battalion commander of Chinese Red Army in 1934 . However he had been a division commander of New Fourth Army in 1945 .

With the rapid expansion of the size of the army, a large number of junior officers and newly recruited students need training. Because of the lack of teachers, the Eighth Route Army dispatched hundreds of military instructors to the New Fourth Army twice. From 1940 to 1942, the New Fourth Army had built established six military training schools in the battlefield . These military training schools were collectively referred to as branches of the Anti-Japanese Military and Political University .

In spring 1938, Chinese Red Army's surviving guerrillas in the South were organized into New Fourth Army's four detachments .

After the New Fourth Army Incident, New Fourth Army was rebuilt in January 1941 .

By the end of World War II, the New Fourth Army had grown to 268,000 men .