 The Vidovdan Constitution adopted by Yugoslavia in 1921 consolidated the country as a centralized state under the Serbian Karađorđević monarchy.Croatian nationalists opposed the centralized state and demanded decentralization and an autonomous Croatia within Yugoslavia, which was accepted by the Yugoslav government in the Cvetković–Maček Agreement of 1939.Serbian nationalists opposed the agreement on the grounds that it weakened the unity of Serbdom, asserting its importance to Yugoslavia with the slogan "Strong Serbdom, Strong Yugoslavia".