<P> A Communist leader addressing survivors of the Long March . </P> <P> During Japan's invasion and occupation of Manchuria Chiang Kai - shek, who saw the CPC as a greater threat, refused to ally with them to fight against the Imperial Japanese Army . Chiang preferred to unite China by eliminating the warlords and CPC forces first . He believed that he was still too weak to launch an offensive to chase out Japan and that China needed time for a military build - up . Only after unification would it be possible for the KMT to mobilize a war against Japan . So he would rather ignore the discontent and anger among Chinese people at his policy of compromise with the Japanese, and ordered KMT generals Zhang Xueliang and Yang Hucheng to carry out suppression of the CPC; however, their provincial forces suffered significant casualties in battles with the Red Army. ref </P> <P> On 12 December 1936, the disgruntled Zhang Xueliang and Yang Hucheng conspired to kidnap Chiang and force him into a truce with the CPC . The incident became known as the Xi'an Incident . Both parties suspended fighting to form a Second United Front to focus their energies and fighting against the Japanese . In 1937 Japan launched its full - scale invasion of China and its well - equipped troops overran KMT defenders in northern and coastal China . </P> <P> The alliance of CPC and KMT was in name only . Unlike the KMT troops, CPC shunned conventional warfare and instead engaged in guerrilla warfare against the Japanese . The level of actual cooperation and coordination between the CPC and KMT during World War II was at best minimal . In the midst of the Second United Front, the CPC and the KMT were still vying for territorial advantage in "Free China" (i.e., areas not occupied by the Japanese or ruled by Japanese puppet governments such as Manchukuo and the Reorganized National Government of China). </P>

Who invaded china in 1937 and occupied the best farmland by 1938