The Invasion of Yugoslavia (code-name Directive 25 or Operation 25) was the Axis powers' attack on the Kingdom of Yugoslavia which began on 6 April 1941 during World War II. The invasion ended with the unconditional surrender of the Royal Yugoslav Army on 17 April 1941, the annexation and occupation of the region by the Axis powers and the creation of the Independent State of Croatia (Nezavisna Država Hrvatska, or NDH).