He commanded divisions against the Bolsheviks (1919–20) and headed a non-parliamentary coalition government in Poland (1922–23). In 1939 he fled to France and organized a Polish army in exile that fought with the Allies in World War II. As head of the exiled Polish government in London he succeeded in maintaining tolerable relations with Moscow until news of the Katyn massacre broke. During his ascendancy Polish prisoners-of-war in the Soviet Union were recruited to form the ‘Polish Army in Russia’ under General Władysław Anders to fight with the Allies. He was killed in an air crash.