In January 1942, the Guangdong people's anti-Japanese East River guerrillas () was established to reinforce anti-Japanese forces in Dongjiang and Zhujiang Pearl River deltas. The guerillas' most significant contribution to the Allies, in particular, was their rescue of twenty American pilots who parachuted into Kowloon when their planes were shot down by the Japanese. In the wake of the British retreat, the guerillas picked up abandoned weapons and established bases in the New Territories and Kowloon. Applying the tactics of guerrilla warfare, they killed Chinese traitors and collaborators. They protected traders in Kowloon and Guangzhou, attacked the police station at Tai Po, and bombed Kai Tak Airport. During the Japanese Occupation of Hong Kong the only fortified resistance was mounted by the East River guerillas.