By the end of the Second Sino-Japanese War, the balance of power in China's civil war had shifted in favour of the Communists. Their main force grew to 1.2 million troops, with a militia of 2 million. Their "Liberated Zone" contained 19 base areas, including 1/4 of the country's territory and 1/3 of its population; this included many important towns and cities.
Moreover, the Soviet Union turned over all of their captured Japanese weapons and a substantial amount of their own supplies to the Communists, who received Northeastern China from the Soviets as well.[49]
In March 1946, despite repeated requests from Chiang, the Soviet Red Army under the command of Marshal Malinovsky continued to delay pulling out of Manchuria while he secretly told the CPC forces to move in behind them, because Stalin wanted Mao to have firm control of at least the northern part of Manchuria before the complete withdrawal of the Soviets, which led to full-scale war for the control of the Northeast. These favourable conditions also facilitated many changes inside the Communist leaders: the more hard-line and firmer force finally gained the upper hand and defeated the opportunists.[49][50] Prior to giving control to Communist leaders, on March 27, Soviet diplomat requested joint venture of industrial development with the Nationalist Party in Manchuria.[51]
Although General Marshall stated that he knew of no evidence that the CPC were being supplied by the Soviet Union, the CPC were able to capture a large number of weapons abandoned by the Japanese, including some tanks
but it was not until large numbers of well trained KMT troops surrendered and joined the communist forces that the CPC were finally able to master the hardware.[52][53] But despite the disadvantage in military hardware,
the CPC's ultimate trump card was its land reform policy. The CPC continued to make the irresistible promise in the countryside to the massive number of landless and starving Chinese peasants that by fighting for the CPC they would be able to take farmland from their landlords.[54]
This strategy enabled the CPC to access an almost unlimited supply of manpower to use in combat as well as provide logistic support, despite suffering heavy casualties throughout many civil war campaigns. For example, during the Huaihai Campaign alone the CPC were able to mobilize 5,430,000 peasants to fight against the KMT forces.
http://en.wikipedia.org/wiki/Chinese_Civil_War