The Pe-2 was first publicly demonstrated in the May Day Parade of 1941. Testing of the Pe-2 was completed and it was accepted for service in June 1941, shortly before the German invasion of the Soviet Union. During the early stages of the invasion, Pe-2 crews, who were poorly trained and unfamiliar with their new aircraft, were often sent on near-suicidal low-level bombing missions against advancing German forces, where they were highly vulnerable to light anti-aircraft guns and German fighters, or bombed from altitude with minimal accuracy and effectiveness against moving troops.