Upon his return to the Balkans in 1918, Broz entered the newly established Kingdom of Yugoslavia, where he joined the Communist Party of Yugoslavia (KPJ). He later was elected as General Secretary, later President, of the League of Communists of Yugoslavia (1939–1980). During World War II, after the Nazi invasion of the area, he led the Yugoslav guerrilla movement, the Partisans (1941–1945).
After the war, he was the chief architect of the Socialist Federal Republic of Yugoslavia (SFRY), serving as both Prime Minister (1944–1963), President (later President for Life) (1953–1980), and Marshal of Yugoslavia, the highest rank of the Yugoslav People’s Army (JNA). Despite being one of the founders of Cominform, he became the first Cominform member to defy Soviet hegemony in 1948. He was the only leader in Joseph Stalin’s time to leave Cominform and begin with his country’s own socialist program, which contained elements of market socialism. Economists active in the former Yugoslavia, including Czech-born Jaroslav Vanek and Yugoslav-born Branko Horvat, promoted a model of market socialism that was dubbed the Illyrian model. Firms were socially owned by their employees and structured on workers’ self-management; they competed in open and free markets.
Tito managed to keep ethnic tensions under control by delegating as much power as possible to each republic. The 1974 Yugoslav Constitution defined SFR Yugoslavia as a “federal republic of equal nations and nationalities, freely united on the principle of brotherhood and unity in achieving specific and common interest.” Each republic was also given the right to self-determination and secession if done through legal channels. Lastly, Tito gave Kosovo and Vojvodina, the two constituent provinces of Serbia, substantially increased autonomy, including de facto veto power in the Serbian parliament. Tito built a very powerful cult of personality around himself, which was maintained by the League of Communists of Yugoslavia after his death. Ten years after his death, as communism collapsed in Eastern Europe, Yugoslavia dissolved and descended into civil war.