Thaddeus Kosciusko (kŏs´ēŭs´kō), Pol. Tadeusz Andrzej Bonawentura Košciuszko, 1746–1817, Polish general. Trained in military academies in Warsaw and Paris, he offered his services to the colonists in the American Revolution because of his commitment to the ideal of liberty. Arriving in America in 1777, he took part in the Saratoga campaign and advised Horatio Gates to fortify Bemis Heights. Later he fortified (1778) West Point and fought (1780) with distinction under Gen. Nathanael Greene in the Carolina campaign. After his return to Poland he became a champion of Polish independence. He fought (1792–93) in the campaign that resulted in the second partition (1793) of Poland (see Poland, partitions of). In 1794 he issued a call at Kraków for a national uprising and led the Polish forces against both Russians and Prussians in a gallant but unsuccessful rebellion that ended with the final partition of Poland. He was imprisoned, and after being freed (1796) went to the United States and later (1798) to France, where after the fall of Napoleon he pleaded with Alexander I of Russia for Polish independence. He died in Solothurn, Switzerland, and is buried in Kraków. His devotion to liberty and Polish independence have made him one of the great Polish heroes.
See studies by M. Haiman (1943, repr. 1975 and 1946, repr. 1977).