The First United Front, formed in 1923, united the Kuomintang and Communist Party of China against warlords and foreign imperialism. This alliance aimed to unify China under a republican government, modernize the nation, and implement social reforms. The Northern Expedition, launched in 1926, was a military campaign led by Chiang Kai-shek to defeat warlords and unify China. Despite initial success, tensions between the KMT and CPC grew, leading to the alliance's breakdown in 1927 and the start of the Chinese Civil War.