During Winter War (1939–1940) Shapiro was Senior Consultant Urologist for evacuation hospitals of Leningrad. Upon the German invasion of Soviet Union (1941) he became a consultant urologist at the Northern Front, and from 1942 to 1945 a chief urologist for evacuation hospitals of the People's Commissariat for Health. His report "Gunshot wounds of the urinary and genital System" at the 1941 All-Union conference of surgeons was well regarded. Thanks to his work as the organizer of the stage treatment of urological wounds, 61% of the victims had their health restored and returned to duty.