PLA(N):
Type 051 destroyer (NATO Luda) class destroyer
Guangzhou (160) in 1974.
On 9 March 1978 at 8:40pm, while the ship was docked in
Zhanjiang Port,
Guangdong Province, it was rocked by a sudden explosion. It sank by 10:55pm.
After nearly half a year of investigation by a joint team of the General Staff, Navy, and Fleet, the explosion was found to have been caused by a lieutenant cadre, Lai Sanyang, who worked in the armoury. Lai had been involved with a woman before joining the navy, but broke off with her after becoming an officer. She then committed suicide. Her family subsequently attempted to raise charges against Lai, so the Political Department of the detachment decided that Lai should be dismissed and demobilized. (An alternate theory postulates that Lai was in fact a suspect for murdering the woman, and had been suspended from duty instead of fully dismissed pending further investigation) But Lai begged his superiors not to demobilize him, as he would be forced to return to his hometown and he had become hated there due to the suicide.
After dismissing Lai Sanyang as a cadre, the unit did not immediately demobilize him. Lai was in charge of sea mines, depth charges, underwater weapons and held the key to the armoury. Following his dismissal, Lai hid in the ammunition depot and detonated the depth charges, sinking the ship. How he achieved this was debated. He either tampered with the mechanism on the charge, or bored a hole through the hull of the ship, which caused water to rush in and detonate the depth charges.
Guangzhou went down with 134 sailors and injuring 28. A tomb was selected for re-burying at a place about 10 meters away from the monument to the ship. In the following days, naval divers continued to retrieve the remains of their comrades in the sea. Afterwards, statistics showed that more than 20 relatively complete remains and 6 large bags of incomplete remains were collected.