Tobruk is a city along the northeastern coast of Libya. When Italy declared war on the British Empire in the 1940s, it became a key Allied base in the North Africa Campaign. It included a deep, and protected, harbor where their warships could be stationed. Tobruk was also in an excellent position to supply the Allied, German and Italian armies in the campaign with convoy supplies arriving at the port.
Before the Italian army invaded Egypt, Tobruk was heavily fortified. That further strengthened the city, which already had considerable natural defenses. To the south of Tobruk were a variety of escarpments and cliffs that could halt advances toward the port over land. With Tobruk on a peninsula, only a minimal number of troops, which could not be bypassed, were required to defend it.
Tobruk was also about 15 miles north of the largest airfield in eastern Libya. The airfield of Sidi Rezegh was one which could provide air support for their troops on the ground. The necessity of aircraft in the wide open desert terrain made Tobruk an even more vital position in Libya.
During the campaign, a number of battles emerged at Tobruk. The first came during Operation Compass during which the British armies pushed the Italians out of Egypt and back into Libya. Operation Compass began as a limited operation to push the Italians back, but by 1941 the Commonwealth forces were winning some notable victories.
Among them was the Battle of Sidi Barrani. With naval and air superiority, the British took Sidi Barrani during the battle. Thousands of Italian troops surrendered, and the British also captured hundreds of guns and additional Italian tanks. After the defeat, the Italians were in full retreat.
During Operation Compass, they sustained the advance up to Tobruk. British and Commonwealth troops reached the outskirts of Tobruk in 1941. During the First Battle of Tobruk, Australian troops surrounded and captured the city. The Allies established a key base at Tobruk on the North African coast that they held up until 1942. After capturing Tobruk, they advanced further and occupied Benghazi. When the operation was over they had captured hundreds of thousands of Italian troops.
Having taken Tobruk, the British turned it in to one their foremost military bases in the North Africa Campaign. There they stationed hundreds of thousands of troops. It was a base for the 8th Army, which was one of Britain's primary formations in North Africa. Hundreds of tanks and planes were also in Tobruk alongside vital oil supplies. They established the Gazala Line around the city to further bolster its defenses.
As a potential forward base, it became a target for the newly formed Afrika Korps in 1941. The Afrika Korps pushed the Allies out of Libya back into Egypt as it advanced towards Tobruk. As Tobruk remained the last Allied position within Libya, the Axis besieged the city during 1941.
Holding Tobruk during the siege was essential as it ensured the Afrika Korps had to bring most of its supplies overland from the port at Tripoli. That diverted troops from the Korps' primary advances. The siege was eventually lifted in the winter of 1941, during Operation Crusader. Then the Axis withdrew to new positions.
However, the Axis drafted new plans to take Tobruk in 1942. During a new advance, the Afrika Korps approached the Gazala Line where the British and Commonwealth troops had dug in. At the Battle of Gazala that followed the British armored divisions had heavy losses against the Afrika Korps' Panzers and anti-tank guns.
When the orders were given for the British to withdraw from the Gazala Line, the Afrika Korps broke through to Tobruk. With the RAF moving to bases too far away from the city, the Allied troops had little in the way of air support and were short of effective anti-tank guns. Consequently, the remaining British and Commonwealth soon surrendered to the Afrika Korps.
After the fall of Tobruk, the Germans and Italians seized thousands of tons of fuel and other supplies located there. With that victory they had won a forward supply base in North Africa, and pressed on towards El Alamein. The Allies defeated their advance at the Battle of El Alamein, and with the Axis in retreat the British later retook Tobruk.
Tobruk remained occupied by the Allies thereafter. Having recaptured Tobruk, and with a flood of U.S. reinforcements pouring in, an Allied victory in the campaign was all but assured by 1943. What was left of the Afrika Korps later surrendered in Tunisia. As a forward supply base, Tobruk had probably been the most vital position for the Allies in the campaign.