[3] During the First World War, Cockchafer was assigned to the defence of the south east coast of England, based at Brightlingsea.

[4] On 17 January 1920, the Insect-class ships Cricket, Cockchafer, Moth, Mantis and Cicala set out from Chatham, England for China.

Cockchafer was stationed on the Yangtze River where her duties were patrolling and protection of British nationals and interests in China.

Wanhsien, now known as Wanzhou District, is a port on the Yangtze River about 1,500 miles (2,400 km) upstream from Shanghai.

Following friction earlier in the year, General Yang's troops seized the British merchant ship, SS Wanhsien in August 1926,[5] which belonged to The China Navigation Company[6] of the Swire Group.

On 29 August 1926,[7] China Navigation Co. ship, SS Wanliu[6] suddenly made a U-turn while a wooden boat full of Chinese soldiers, guns, bullets and allowances passed by.

General Yang seized several of Cockchafer's Chinese crewmembers who were ashore and one was killed in full view of the rest of the crew.

On 1 September 1926 Widgeon arrived at Wanhsien but negotiations did not go well and the rear admiral on the Yangtze decided that the matter would have to be settled by force.

The boarding party aboard SS Wanhsien suffered a number of casualties including the senior British officer from Despatch and Cockchafer's sub-lieutenant who were killed.

She played host to the regent of Iraq, Amir Abdul Illah who had been deposed and fled an assassination plot in Baghdad.

The purpose of the invasion was to secure Iranian oil fields and ensure supply lines (see Persian Corridor) for the Soviets fighting against Nazi Germany on the Eastern Front.