Józef Klemens Piłsudski (5 December 1867 – 12 May 1935) was a Polish statesman and soldier. He held the office of Chief of State (1918–22) in the early years of the Second Republic of Poland, and then served as the country's de facto dictator (1926–35) while holding the office of Prime Minister and as the General Inspector of the Armed Forces. He was also the first soldier to hold the rank of Marshal of Poland.
From mid-World War I he had a major influence in Poland's politics, and was an important figure on the European political scene. He is considered largely responsible for Poland regaining its independence in 1918, after 123 years of partitions. Piłsudski managed to wrestle the control of Wilno from Lithuania, but was unable to incorporate much of his Lithuanian homeland into the newly resurrected Polish State.
Early in his political career, Piłsudski became a leader of the Polish Socialist Party. Concluding, however, that Poland's independence would have to be won by force of arms, he created the Polish Legions. In 1914 he anticipated the outbreak of a European war, the Russian Empire's defeat by the Central Powers, and the Central Powers' defeat by the western powers. When World War I broke out, he and his Legions fought alongside the Austro-Hungarian and German Empires to ensure Russia's defeat. In 1917, with Russia faring badly in the war, he withdrew his support from the Central Powers.
From November 1918, when Poland regained independence, until 1922, Piłsudski was Poland's Chief of State. In 1919–21 he commanded Poland's forces in the Polish-Soviet War. In 1923, with the Polish government dominated by his opponents, particularly the National Democrats, he withdrew from active politics. Three years later he returned to power with the May 1926 coup d'état, and became the de facto dictator of Poland. From then until his death in 1935, he concerned himself primarily with military and foreign affairs.
Piłsudski pursued two complementary strategies intended to enhance Poland's security: "Prometheism", which aimed at breaking up, successively, Imperial Russia and the Soviet Union into their constituent nations; and the creation of an Intermarum federation, comprising Poland and several of her neighbors. Though a number of his political acts remain controversial, Piłsudski's memory is held in high esteem in Poland.
Jozef Pilsudski had waged war against Russia during the Russian Civil War, expanding Polish territory into territory claimed by both Russia and the newly-independent Lithuania. Russia's successor state, the Soviet Union, pressed irredentist claims against Poland for the territory Pilsudski had "stolen." In 1939, the Soviet Union went to war to make good on these claims and retake the land Pilsudski had seized.