On 6 April 1941, the Kingdom of Yugoslavia was invaded from all sides by the Axis powers, primarily by German forces, but also including Italian, Hungarian and Bulgarian formations. During the invasion, Belgrade was bombed by the "Luftwaffe". The invasion lasted little more than ten days, ending with the unconditional surrender of the Royal Yugoslav Army on 17 April. Besides being hopelessly ill-equipped when compared to the Wehrmacht, the Army attempted to defend all borders but only managed to thinly spread the limited resources available.