Churchill, reacting to the fall of Tobruk, flew to Egypt to review the situation, then replaced Auchinleck with General William Gott. But Gott was killed while flying to take command, so Churchill transferred General Bernard Montgomery and sent him to command the British forces in Egypt. Montgomery, a by-the-book military man, immediately set about strengthening the Eighth Army. He replaced officers he considered lacking in leadership, increased troop training, and arranged for closer air support.

Montgomery correctly assumed that Rommel would attempt to break through at the south end of the line in August, and made sure his Eighth Army was prepared. Rommel attacked on August 31 at exactly the spot Montgomery had anticipated and was quickly repelled by blistering fire. Unable to proceed, Rommel was forced to withdraw.

While Rommel was trying to break the El Alamein line, RAF bombers were doing all they could to destroy the German tanker convoy that was bringing the Desert Fox the fuel he needed to continue. Meanwhile, Montgomery enjoyed a plentiful resupply effort from the United States. At Churchill's request, President Roosevelt had authorized the loan of Sherman tanks and artillery to assist Montgomery's defense.

Two months after Rommel's ineffective drive against the El Alamein line, Montgomery began a remarkably strong offensive campaign designed to force the German-Italian forces into a retreat. The Eighth Army quickly decimated four German divisions and eight Italian divisions and captured nearly 30,000 prisoners. Montgomery then turned his attention to the fleeing Rommel. On November 20, 1942, Benghazi fell, and three days later Rommel was back where he started, in El Agheila. The Eighth Army chased Rommel through Libya, taking Tripoli on January 13, 1943, and eventually made its way to French North Africa, where it hooked up with other Allied troops in April.