 The CPC's Red Army fought alongside KMT forces during the Battle of Taiyuan, and the high point of their cooperation came in 1938 during the Battle of Wuhan.Despite Japan's steady territorial gains in northern China, the coastal regions, and the rich Yangtze River Valley in central China, the distrust between the two antagonists was scarcely veiled.The uneasy alliance began to break down by late 1938, partially due to the Communists' aggressive efforts to expand their military strength by absorbing Chinese guerrilla forces behind Japanese lines.