Deutscher was born in 1907 near Krakow and joined the Polish Communist Party in 1926. After his expulsion in 1932, he maintained his opposition to the general drift of Comintern policy in the 1930s. He moved to London in 1939 and continued his journalistic activity until 1946, devoting the rest of his life to historical research and writing of books and essays. He died in 1967.