In 1940 Lorenz became a professor of psychology at the University of Königsberg. He was drafted into the Wehrmacht in 1941. He tried to become a motorcycle mechanic, but instead he was assigned as a medic. He was a prisoner of war in the Soviet Union from 1942 to 1948. During this time, he continued to work as a medical doctor and "got quite friendly with some Russians, mostly doctors". When he was sent back home after the war, he was allowed to keep both the manuscript of the book he had been writing and his pet starling. He arrived back in Altenberg "with manuscript and bird intact." The manuscript became his book "Behind the Mirror". 