From April 1919, the Lithuanian–Soviet War dragged on parallel with the Polish–Soviet War. Polish troops captured Vilnius from the Soviets on 21 April 1919. Poland had territorial claims over Lithuania, especially the Vilnius Region, and these tensions spilled over into the Polish–Lithuanian War. Józef Piłsudski of Poland, seeking a Polish-Lithuanian federation, but unable to find common ground with Lithuanian politicians, in August 1919 made an unsuccessful attempt to overthrow the Lithuanian government in Kaunas.