He was a leader of the Hungarian revolution of 1848 . Petofi joined Polish revolutionary general Józef Bem's Transylvanian army, fighting a successful campaign against Habsburg troops, Romanian and Transylvanian Saxon militias. However, it was defeated repeatedly when Imperial Russia intervened to aid the Austrians. He was last seen in the battle of Segesvár (Sighisoara), July 31, 1849. The circumstances of his death are mysterious.The main opinion is that he died in the battle, based on the account of a Russian military doctor in his diary.