What contributed to the downfall of China's republic?

Chiang Kai-shek seized power as a dictator.

Warlords overthrew president Sun Yat-sen.

China's presidents did not have enough power.

Nationalists attacked the republican government.

China's presidents did not have enough power. Chinese nationalists represented the republic faction, who fought against the communist faction lead against Mao Zedong in a Chinese Civil War that started before World War II and resumed afterwards, resulting in a Communist victory in 1949. This political war was started from the various warlords who wished to dominate their own part of the China during the Republic. This fragmented a strong central political unity amongst the government, resulting in a government collapse from weak presidents who lacked strong unity.