Their long-term goals simply did not embrace mutual accommodation, and in the short term they each used the cover of the Marshall mission to their advantage. Marshall arrived in China on 20 December 1945 and initially achieved impressive results, as a cease-fire was established on 10 January 1946. That same month, a Political Consultative Council, with representatives from all of China's warring parties, agreed to the outlines of a new, more democratic political system that would be discussed further via the National Assembly. Finally, in February, the communists agreed to merge their military with the Nationalist army on the condition that military and political reorganization proceeded simultaneously.
The fly in the ointment, however, turned out to be North China and Manchuria. U.S. policy was to transport Jiang's troops there to take over from the defeated Japanese and establish order. Understandably, Mao viewed this with considerable suspicion. Moreover, Soviet forces had entered Manchuria to fight the Japanese in August 1945 but had withdrawn in April 1946, leaving behind a vacuum into which the warring factions expanded. When the communists captured Changchun on 18 April 1946, Jiang expanded the conflict, and despite Marshall's efforts to secure a cease-fire, China was once again engaged in civil war. Early victories against the communists emboldened Jiang, and he laid down unacceptable political terms as the price for reestablishing the cease-fire. A brief lull in June offered some hope, but by July Marshall had concluded that Jiang was not interested in a long-term cease-fire; rather, he was set on wiping out the communists.
Marshall sought to rescue the mission from complete collapse with the assistance of U.S. Ambassador to China John Leighton Stuart, who was trusted by the communists, and by cutting off U.S. arms shipments to Jiang. Simultaneously, President Truman called for progress, without which U.S. policy toward China might change. On 30 September 1946, however, Jiang announced an attack on Kalgan, a town in Inner Mongolia held by the communists. Nationalist forces captured it in October, conceding to a cease-fire a month later. On his own terms, Jiang also summoned the National Assembly. The communists, understandably, stayed away.
By October, Marshall had concluded that a political solution was impossible. He had also concluded that U.S. military intervention was not a viable solution. American diplomacy in China had reached the end of the road. Marshall returned to the United States in January 1947 as the Chinese Civil War continued.
U.S. Department of State. The China White Paper, Vol. 1, August 1949. Washington, DC: U.S. Government Printing Office, 1949.; Westad, Odd Arne. Cold War and Revolution: Soviet-American Rivalry and the Origins of the Chinese Civil War, 1944–1946. New York: Columbia University Press, 1993.