When Duan Qirui refused to validate the Constitution Cheng and fellow Admiral Lin Baoyi sailed their fleets down south to join with the 'Constitutional government' of Sun Yat-sen. He was assassinated in Haizhu District, Guangzhou, in 1918.
Duan Qirui's refusal to support the Constitution led to a split between him and Cheng, who then allied with Admiral Lin Baoyi and Sun Yat-sen's 'Provisional government', resulting in Duan's assassination in Haizhu District, Guangzhou, in 1918.