What was the significance of the battles of El Alamein, Guadalcanal and Stalingrad?

El Alamein was actually two major battles, not one, fought in the North African campaign of World War II between Field Marshal Erwin Rommel's primarily German forces and the British 8th army. The first battle of El Alamein ended in a stalemate, with heavy casualties on both sides. The second battle of El Alamein is the more famous one, as it was a major turning point in the North African campaign. The Allies thoroughly defeated Rommel's forces in the battle, marking the beginning of the Axis's defeat in the campaign.

Guadalcanal was a similar story. Japan had been incredibly successful in the Pacific campaign over the first few years of the war and had expanded on a huge scale, occupying land all the way from the Solomon Islands to modern-day Vietnam. The battle of Guadalcanal was the first major land battle conducted by Allied forces against Japan in the Pacific. It was the beginning of the American island-hopping campaign, which led to Japan's eventual defeat.

Stalingrad was also where the tide turned against the Axis on the Eastern Front. The Germans had advanced through thousands of miles of Soviet territory, capturing key cities like Kyiv and Minsk, until Army Group South came to the major Soviet city of Stalingrad. As the city bore the name of the nation's leader, and for other reasons such as order No.227 (the "not a step back" order), the Soviets were determined to defend the city. This resulted in one of the heaviest battles of World War II, in the aftermath of which the city was completely destroyed, but Germany was very much on the defensive as they were pushed back.