Efim Sher was born in 1923 in Wilno (now Vilnius), at that time a Polish city. From a young age, he encountered grassroots antisemitism, and was forced to carry a knuckle-duster with him. In 1938, the 15-year-old Sher joined an underground Communist cell. Later he recalled that the main motive that brought him into this organization was the "national [i.e. ethnic] question". In October 1939, Wilno was annexed to Lithuania and became its capital city Vilnius and, between June and August 1940, all of Lithuania was annexed to the Soviet Union. Sher's Communist cell then merged with Soviet Komsomol (Young Communist League).
On June 22, 1941, the first day of the German invasion of the Soviet Union, in the morning, Komsomol members were mobilized for para-military activity; e.g. Sher was sent to guard a power station although he had no weapon, even a rifle. On the next day, Sher and his comrades decided to leave the doomed city on their own. Relatively old, Sher's parents refused to leave together with him. Despite all the difficulties and obstacles, the young people managed to reach Russia.
It was in Smolensk, western Russia, where Sher realized that he would never see his parents, his sister, and other relatives again. He was shocked by this. In Smolensk he and his comrades attempted to volunteer to join the Red Army, but were rejected on two grounds: they were only 17 years old and specific Baltic divisions had still not begun to be formed. Instead, they were mobilized for work, first on a kolkhoz, then at a magnesium-producing plant in Berezniki, Urals.
In 1943, Sher was drafted into the Red Army. He became a soldier in a mortar battalion of the 16th Lithuanian Division, under the command of Vulf Vilenskii. His baptism of fire was in June 1944, in eastern Prussia. In Prussia, he was wounded, but returned to combat. In November 1944, NCO Efim Sher, then the commander of a mortar platoon, was transferred to Latvia, to the take part in the liquidation of the enemy's Courland Pocket. There he was seriously wounded by a shell. Fortunately, Sher was sent to a military hospital in Moscow. There Efim learned that Avrom Sutskever, a Yiddish poet from Vilnius, who had been a friend of his father, lived close to the hospital. Sher visited Sutskever, himself a survivor of the Vilnius ghetto, who told Sher that his family had perished in the ghetto.
After his demobilization, Sher refused to return to Vilnius. "I could not live in my home city. Every street, every step brought me back to my youth, to the good time when my parents, sister, relatives, school friends were still alive. Thoughts about their terrible death did not let me rest. ... And so I left Vilnius" – recalled Sher after the war [Kniga zhivykh: Vospominaniia ievreiev-frontovikov, uznikov getto i natsistskikh kontslagerei, boitsov partizanskikh otriadov, zashchitnikov blokadnogo Leningrada (The Book of the Living: Memoirs of Jewish Front-line Fighters, Prisoners of Ghettos and Nazi Concentration Camps, Partisan Fighters, (and) Defenders of Besieged Leningrad), St. Petersburg, 1995]. Sher settled in Leningrad (St. Petersburg), qualified as an acoustical engineer, and worked in the film industry and on the construction of movie theaters and concert halls in this city.