The Siege of Tobruk took place between 10 April and 27 November 1941, during the Western Desert campaign (1940–1943) of the Second World War. An Allied force, consisting mostly of the 9th Australian Division, commanded by Lieutenant-General Leslie Morshead, was besieged in the North African port of Tobruk by German and Italian forces. The tenacious defenders quickly became known as the Rats of Tobruk. After 231 days, they were finally relieved by the British Eighth Army.

The Western Desert campaign took place in the deserts of Egypt and Libya and was the main theatre in the North African campaign of the Second World War. Military operations began in June 1940 with the Italian declaration of war and the Italian invasion of Egypt from Libya in September. Operation Compass, a five-day raid by the British in December 1940, was so successful that it led to the destruction of the Italian 10th Army over the following two months. Benito Mussolini sought help from Adolf Hitler, who sent a small German force to Tripoli under Directive 22. The Afrika Korps was formally under Italian command, as Italy was the main Axis power in the Mediterranean and North Africa.