Tuđman was born in Veliko Trgovišće. In his youth he fought during World War II as a member of the Yugoslav Partisans. After the war he took a post in the Ministry of Defence, later attaining the rank of major general of the Yugoslav Army in 1960. After his military career he dedicated himself to the study of geopolitics. In 1963 he became a professor at the Zagreb Faculty of Political Sciences. He received a doctorate in history in 1965 and worked as a historian until coming into conflict with the regime. Tuđman participated in the Croatian Spring movement that called for reforms in the country and was imprisoned for his activities in 1972. He lived relatively anonymously in the following years until the end of communism, whereupon he began his political career by founding the Croatian Democratic Union (HDZ) in 1989.