The infamous warlord during World War II known for his brutal tactics in China was Chiang Kai-shek’s counterpart, the warlord Zhang Zhizhong, or the notorious Zhang Xueliang, who was involved in various brutal military campaigns. Zhang Xueliang, often referred to as the "Young Marshal," initially commanded forces during the Second Sino-Japanese War but later had a complex collaboration and conflict with the Nationalists. His infamous actions were characterized by violence and suppression against rival warlords and the Japanese invaders, contributing to the war's profound impact on the Chinese populace and signaling deep issues in China's war efforts and governance.