Why did jiang and Mao form an alliance?

Answer 1

They temporarily united to fight off the invading forces of Japan. The first time Japan invaded a little part of China, Jiang (who was leader of china at the time) didn't really care. But the second time it was the actual mainland of China, so Mao Zedong and Jaing Jieshi saw it to be in the interest of China to unite and fight off the Japanese.

Answer 2

Mao Tse Tung (Communist Army) and Chiang Kai-Shek (National Revolutionary Army)

never joined forces in World War 2. In fact when soldiers from the National Revolutionary army found themselves in between the communists and the Imperial Japanese Army, they generally joined the IJA as collaborators.

Occasionally, under direction and pressure of the Americans (Joe Stillwell), the National revolutionary would work in concert with the communists against the japanese, but this was rare and only occurred towards the end of WW2.

The Communists and the National Revolutionary Army never joined forces.

The Communists and the National Revolutionary Army and assorted Regional Warlords, were in a bitter ruthless civil war for control of china during the 30's and 40's. The IJA was considered a lesser threat and given lower priority and far less soldiers then those already dedicated to fighting the civil war. Against the IJA, the National Revolutionary Army, tended to avoid battle and follow a program of scorched earth, to deny the IJA the fruits of their victories. This resulted in horrendous civilian casualities, especially when the NRA burned down cities that were in danger of being captured by IJA.