Why was the fall of Tobruk considered a major disaster for Britain?

The fall of Tobruk on June 21, 1942, was considered a major disaster for Britain because it represented one of the most significant military defeats of the war, second only to the fall of Singapore.1

The catastrophe was multifaceted:

• Loss of Personnel: The surrender resulted in the capture of a 33,000-man garrison, dealing a severe blow to British manpower in the North African theater.1
• Material Losses: The Allies lost an immense quantity of military stores and equipment, which significantly weakened their defensive capabilities.12
• Strategic Collapse: The defeat followed the destruction of the bulk of British armored strength during the preceding battles at the "Cauldron." With the Eighth Army forced into a rapid retreat toward the Egyptian frontier, the loss of the fortress left the path toward Egypt and the Suez Canal dangerously exposed to Erwin Rommel’s forces.13