Croatian officers and sailors continued to man the new Royal Yugoslav Navy (1918–1941) until its demise during the Axis invasion of Yugoslavia. During World War II Croatian partisans formed a guerilla Partisan Navy consisting of makeshift vessels in 1942, resisting Italian (and later German) occupation of the Adriatic. In the later phases of the war, they cooperated closely with the Royal Navy. After the war, Socialist Yugoslav Navy, sprung up from the partisan navy, had Split as its HQ and mainly used shipyards in Šibenik, Split, Kraljevica, Rijeka and Pula.