Moshe Beirach was raised in a Jewish family in Pabianice, Poland. After Germany invaded Poland in 1939 he had to perform forced labor for the occupiers. He fled to Belorussia.
In June 1941 German troops also entered Belorussia. A year later, Beirach barely survived the massacre of the Jewish population in Zhaludok. He was among the few Jews who were spared in order to work for the occupiers. Beirach was interned in various ghettos and labor camps. In May 1943 he managed to escape from the Shchuchyn ghetto into the surrounding forests. His future wife Pesia Levit escaped with him. The two of them joined the Jewish partisan unit of Tuvia Bielski and survived in Bielski’s forest camp.
After liberation Beirach learned that his parents and siblings had been murdered.
Moshe and Pesia Beirach fled the Soviet regime in 1945 and went to Palestine. In 1967 Beirach appeared as a witness in the trial against those responsible for the massacre in Zhaludok.