The Battle of El Alamein in 1942 was the most significant battle in North Africa. Overall, it was a WW2 battle that decided the outcome of the desert war. It more specifically refers to the Second Battle of El Alamein as opposed to one that preceded it.
The North Africa Campaign began in 1940 after the Italian army advanced into Egypt. German reinforcements sent to Africa ensured the rise of the Afrika Korps in 1941, which rejuvenated the campaign for the Axis. Undoubtedly, the highlight was their victory at the Battle of Gazala, but despite this a more general victory in the North Africa Campaign had not been won.
After the Battle of Gazala in 1942, the Afrika Korps occupied Tobruk. This also boosted its supplies, which were stretched during the campaign. Fuel was especially critical to the Axis, as well as the Allies; and at Tobruk the Germans and Italians seized additional fuel supplies.
However, despite his victory at Gazala, Rommel’s supplies were still stretched. The North Africa Campaign was not a primary front for the Germans, so the Afrika Korps could not count on a great number of potential reinforcements. In addition to this, the SAS also further undermined Rommel’s supply line.
Germany was also at war with the Americans, although U.S. troops had yet to arrive in North Africa. However, the U.K. expected them to arrive to bolster the British and Commonwealth soldiers in Africa. When they did arrive, there would be little to no chance of any victory for Germany and Italy. As such, the Axis had to win quickly, or not at all.
The Suez Canal was the primary target for the Afrika Korps in the North Africa Campaign. This was a key Allied supply route, and if taken Suez would also provide Germany with potential oil supplies in the Middle East. To win the war in North Africa, the Afrika Korps had to maintain its advance towards the Suez Canal.
As such, El Alamein became the next target for the Axis' advance. Britain had to halt the enemy onslaught here, otherwise the loss of El Alamein would leave an open pathway towards the Suez Canal. The Afrika Korps could not delay further advances, so headed for El Alamein.
The El Alamein battle was an essential one for both sides. The British army had already been routed at Singapore and Gazala, and needed a victory not only to halt the Afrika Korps advance, but to highlight that Britain and its allies could still win the war. With more limited supplies, the Axis had to take El Alamein ASAP if they were to reach the Suez Canal.
The Afrika Krops had pushed Britain out of Libya and back into Egypt. Thus, the possibility of an Axis victory remained as Rommel's troops approached El Alamein in 1942. However, Rommel was aware that the Allies would be increasingly re-enforced; so he first attempted to defeat the British army at the First Battle of El Alamein. The U.K. halted this final Axis advance into Egypt.
As such, the Eighth Army was ready for Rommel's soldiers at the Second Battle of El Alamein. Almost 200,000 Commonwealth troops fought and defeated the Germans and Italians at El Alamein. Under Montgomery the Eighth Army attacked the north and south of the Axis line and then broke through with tanks. The Axis retreated to El Aghelia.
The retreat all but ended the Axis chances of victory in Africa. Egypt and the Suez Canal remained out of reach of the Afrika Korps. It marked the beginning of the end of the war in North Africa, as the Allies began to pursue the remaining German troops.
During the Battle of El Alamein, the Allies gained a clear military superiority in Africa. With little prospect of further supplies and reinforcements for the Axis armies in North Africa, any potential victory diminished as the Allies military equipment and materials expanded. Therefore, the Battle of El Alamein was the 'end of the beginning' in North Africa. Victory was not won there, but at any rate it gave the Allies clear military superiority.
In the aftermath of the battle Rommel had lost over a quarter of his troops. The Axis had an estimated 30, 542 casualties during the battle. This also included the loss of up to 500 tanks and other military equipment.
In comparison, the British had half that number. In total, the Eighth Army had roughly 13,000 casualties at El Alamein. It also lost more than 300 tanks during the battle.
The Afrika Korps still had the majority of its army left. Consequently, the Axis made a fighting withdrawal from El Alamein towards El Aghelia. Montgomery flanked El Aghelia, forcing the Germans and Italians into further retreat.
Hereafter, Operation Torch began in North Africa. Operation Torch was the Allied landings in French North Africa. Hoping that the French would provide little resistance to the Allied landings, they were in fact taken by surprise as Vichy French troops organized an effective defense. Only thanks to the Free France movement were these troops neutralized.
The U.S. troops in North Africa had increased in number, so the Allies were being re-enforced. Increasing Allied military superiority was beginning to tell, and the path to victory in North Africa was clear.
Britain and the USA planned a campaign in Tunisia to push the Axis out of Africa. To this extent it succeeded, as the Allies moved into Tunis. Hundreds of thousands of German and Italian troops surrendered to the Allies. The remaining Axis troops retreated to Italy.
Therefore, the Allies had won victory in Africa. The Allied oil supplies were preserved, and better still the pathway further opened in the Mediterranean. Italy was now open for an allied invasion which would allow for the Allies to establish a second front on mainland Europe.
As such, the Allies landed on Italy later in 1943 to finish off those remaining Italian armies beaten in Africa. The Italians could not organize an especially effective defense as the Allies landed on Sicily. However, as defeat for fascist Italy became eminent German reinforcements considerably strengthened Axis resistance.
Despite this, Italian civilians started to side with the Allies; and it became clear that support for Mussolini's Italy had largely evaporated. Fascist Italy was all but defeated, and only a German military presence could preserve a fascist state in northern Italy. Italy slipped into a state of Civil War as pro-fascist and anti-fascist groups clashed with the support of the German and allied armies.
The El Alamein battle undoubtedly tipped the North Africa Campaign in the Allies favor. The defeat of Afrika Korps at El Alamein pushed the Axis into retreat. With increasing reinforcements, the Allies held all the cards in 1943; and the Axis surrendered at Tunisia. From here fascist Italy was left open to land on, and the Italians were all but defeated by the Allies.