Following the First World War and the dissolution of Austria-Hungary (1918), Croatian lands were incorporated into the Kingdom of Yugoslavia, which was dominated by Serbia. Following the German invasion of Yugoslavia in April 1941, the Independent State of Croatia allied to the Axis powers was established to be defeated in May 1945, a week after the German Instrument of Surrender. The Socialist Republic of Croatia, a constituent republic of the Socialist Federal Republic of Yugoslavia, was constituted. In 1991, Croatia′s leadership severed ties to Yugoslavia and proclaimed independence amidst the dissolution of Yugoslavia .