In World War I he was captured on the Russian front and joined the Bolsheviks. He was sent back to Hungary to form a communist party and in March 1919 persuaded the Hungarian communists and Social Democrats to form a coalition government and to set up a communist state under his dictatorship. His Red Army overran Slovakia, but promised Soviet help was not forthcoming. In May 1919 he was defeated by a Romanian army of intervention. Kun fled the country and is assumed to have been liquidated in one of Stalin’s purges.