Yakovlev graduated from secondary school days before Nazi Germany invaded the Soviet Union. He was drafted into the Red Army in November 1941, with brief training, and was promoted to lieutenant in a rifle platoon during the War. He served as a platoon commander in Volkhov Front. On August 6, 1942, he was leading 30 Chuvash peasants and was ordered to charge German positions in Vinyagolovo near Leningrad and was badly wounded. He was hospitalized until March 1943, and almost required an amputation, but was saved at the last moment. He became a member of the Communist Party of the Soviet Union in 1944. At this time he regarded the Communist Party as "life's truth" and affirmed he was totally loyal and faithful to Soviet Union, and he was an ardent admirer of Stalin.