90 years ago, on April 12, 1927, the leader of the ruling Kuomintang party and the commander-in-chief of the National Revolutionary Army of China, Chiang Kai-shek, staged a massive terror in Shanghai against his former allies, the Communists. More than 4,000 people were killed, including many prominent leaders of the Chinese Communist Party. The pretext for the massacre was the accusation that the Communists were trying to seize power and bring the Kuomintang under their control.