Some practical combat experience had been gained in participating in the Spanish Civil War, and against Japan in the Far East. Shortly before the start of war with Germany a Soviet Volunteer Group was sent to China to train the pilots from the Republic of China Air Force for the continuing war with the Japanese. However, these experiences proved of little use in the Winter War against Finland in 1939, where scores of inexperienced Soviet bomber and fighter pilots were shot down by a relatively small number of Finnish Air Force (FAF) pilots. The VVS soon learned established Soviet air defence procedures derived from the Spanish Civil War, such as forming defensive circles when attacked, did not work well against the Finns, who employed dive-and-zoom tactics to shoot down their Soviet opponents in great numbers. The effects of the Great Purge undoubtedly played a role in the slow reaction of the "VVS" and its command to the new realities of air combat. The Soviet Air Force as well as the Soviet aircraft industry would eventually learn from these combat experiences, though not before the German invasion of the Soviet Union in 1941.