The terms Apostasia (, "Apostasy") or Iouliana (, "July events") or the Royal Coup ( "To Vasiliko Praxikopima") are used to describe the political crisis in Greece centered on the resignation, on 15 July 1965, of Prime Minister Georgios Papandreou and subsequent appointment, by King Constantine II, of successive prime ministers from Papandreou's own party, the Center Union, to replace him. Defectors from the Center Union were branded by Papandreou's sympathizers as Apostates ("renegades"). The "Apostasia" heralded a prolonged period of political instability, which weakened the fragile post-civil war order, and ultimately led to the establishment of the military regime in April 1967.