The May Coup (Polish: przewrót majowy or zamach majowy) was a coup d'état carried out in Poland by Marshal Józef Piłsudski from 12 to 14 May 1926. The attack of Piłsudski's supporters on government forces resulted in an overthrow of the democratically-elected government of President Stanisław Wojciechowski and Prime Minister Wincenty Witos and caused hundreds of fatalities. A new government was installed, headed by Kazimierz Bartel. Ignacy Mościcki became president. Piłsudski remained the dominant politician in Poland until his death in 1935.