Complex sentence: After his graduation he joined the Northern Expedition under Generalissimo Chiang Kai Shek against the northern warlords, after Chiang purged the communists in Shanghai on April 12,1927 he stayed with the Kuomintang as a regiment commander in the National Revolutionary Army.
Split into simpler sentences: After his graduation he joined the Northern Expedition under Generalissimo Chiang Kai Shek against the northern warlords. After Chiang purged the communists in Shanghai on April 12,1927, he stayed with the Kuomintang as a regiment commander in the National Revolutionary Army.