Reicin was born into a poor Jewish family (his birth name was Reinzinger, sometimes written as Reicinger). He first studied at a gymnasium, and later at a business college from which he was expelled after discovery of his activism for the communist party. In the 1930s, Reicin became a functionary of a communist youth organization and contributor of the party newspaper Rudé Právo. After the occupation of Czechoslovakia by Nazi Germany in 1939, he was imprisoned by the Gestapo. He was released after seven months and, in 1940, he managed to flee into the Soviet Union. There he worked as a radio propagandist. After the attack by Germany on Soviet Union, he was interned (as were many people having Protectorate of Bohemia and Moravia citizenship). In February 1942, he joined the newly formed Fir