(a collective Presidency was formed after Tito's death in 1980). Also important were the Communist Party general secretaries for each republic and province, and the general secretary of Central Committee of the Communist Party. Tito was the most powerful person in the country, followed by republican and provincial premiers and presidents, and Communist Party presidents. Slobodan Penezić Krcun, Tito's chief of secret police in Serbia, fell victim to a dubious traffic incident after he started to complain about Tito's politics. Minister of the interior Aleksandar Ranković lost all of his titles and rights after a major disagreement with Tito regarding state politics. Some influential ministers in government, such as Edvard Kardelj or Stane Dolanc, were more important than the Prime Minister. First cracks in the tightly governed system surfaced when students in Belgrade and several other cities joined the worldwide protests of 1968. President Josip Broz Tito gradually stopped the protests by giving in to some of the students' demands and saying that "students are right" during a televised speech. But in the following years, he dealt with the leaders of the protests by sacking them from university and Communist party posts. A more severe sign of disobedience was so-called Croatian Spring of 1970 and 1971, when students in Zagreb organised demonstrations for greater civil liberties and greater Croatian autonomy, followed by mass manifestations across Croatia. The regime stifled the public protest and incarcerated the leaders, though many key Croatian representatives in the Party silently supported this cause. As a result, a new Constitution was ratified in 1974, which gave more rights to the individual republics in Yugoslavia and provinces in Serbia. Ethnic tensions and economic crisis After the Yugoslav Partisans took over the country at the end of WWII, nationalism was banned from being publicly promoted. Overall relative peace was retained under Tito's rule, though nationalist protests did occur, but these were usually repressed and nationalist leaders were arrested and some were executed by Yugoslav officials. However, the Croatian Spring protests in the 1970s were backed by large numbers of Croats who claimed that Yugoslavia remained a Serb hegemony and demanded that Serbia's powers be reduced. Tito, whose home republic was Croatia, was concerned over the stability of the country and responded in a manner to appease both Croats and Serbs: he ordered the arrest of the Croat protestors, while at the same time conceding to some of their