The siege of Tobruk lasted for 241 days in 1941, after Axis forces advanced through Cyrenaica from El Agheila in Operation Sonnenblume against Allied forces in Libya, during the Western Desert Campaign of the Second World War. In late 1940, the Allies had defeated the Italian 10th Army during Operation Compass and trapped the remnants at Beda Fomm. During early 1941, much of the Western Desert Force was sent to the Greek and Syrian campaigns. As German troops and Italian reinforcements reached Libya, only a skeleton Allied force remained, short of equipment and supplies.
Operation Sonnenblume, forced the Allies into a retreat to the Egyptian border. A garrison, consisting mostly of the 9th Australian Division remained at Tobruk, to deny the port to the Axis, while the WDF reorganised and prepared a counter-offensive. The Axis siege of Tobruk began on 10 April, when the port was attacked by a force under Generalleutnant Erwin Rommel and continued during three relief attempts, Operation Brevity, Operation Battleaxe and Operation Crusader.