On April 18, 1942, the United States launched the Doolittle Raid, an attack by 16 B-25 Mitchell bombers from the aircraft carrier USS Hornet on Tokyo, Nagoya, and Yokohama.

Because the raid had to be launched earlier than planned, all but one of the aircraft (which against orders diverted to the Soviet Union) ran out of fuel and crashed in the Chinese provinces of Zhejiang and Jiangxi or their offshore islands.

Two days before the Doolittle Raid, Headquarters set up an operational plan with the goal of defeating Chinese forces and destroying air bases.

On May 15, the main force of the Japanese 13th Army invaded westward along the Zhejiang-Jiangxi Railway and both sides from Fenghua, Shangyu, Shaoxing, Xiaoshan and other towns in Zhejiang.

[12] This attack took place at Jinhua in Zhejiang and the Japanese soldiers inadvertently advanced in the area they spread with biological weapons and got themselves infected,[13][14][15][16][17] leading to over 1,700 dying and 10,000 getting sick.