There are many discussions on what were the turning points in World War II, and they usually regard two of them. One of the turning points is suggested to take place in battles between the United States and Japan, and the second one between the Soviet Union and Germany. The most discussed battles that possibly created or marked the momentum of the remaining part of the war are the battle of Midway, where the United States were able to gain advance, and the battles of Kursk and Stalingrad, after which the Soviet troops were able to start moving towards Germany.
The Battles in Kursk and Stalingrad were truly devastating for both Germany and the Soviet Union. Many call the battle of Stalingrad a turning point in the war, yet a crucial victory was obtained in the battle for Kursk. The soviets had major advantages regarding the number of tanks, yet German tanks were much more powerful. Eventually, the Germans were not able to advance in breaking the defense of the Soviet Union in the battle of Kursk, and the Soviet Union and Allies started moving West. In the first months of the attack on pearl harbor, Japan was very successful in battles (Weinberg 2013). Yet, the Battle of Midway changed this, as the US gained advance and finally started counter-offensive actions. The Japanese navy suffered serious losses and was forced to return home. American forces assaulted the Japanese in the Solomon Islands in August 1942, forcing a costly retreat of Japanese forces from Guadalcanal in February 1943. In the Pacific, Allied troops gradually achieved naval and air superiority, and they proceeded systematically from island to island, capturing them while suffering heavy losses.
Considering these factors, the battles of Kursk and Midway can be called turning points. The battle of Midway initiated the counter-offensive actions of the Allies in the Pacific, whereas the battle of Kursk is more arguable in terms of creating momentum. The opportunity for the movement of Soviet troops to Germany was determined not only by the battle of Kursk, yet it can be considered a marker of when the turning point happened, even if it was not its only cause.
Reference
Weinberg, Gerhard L. 2013. A World at Arms: A Global History of World War II. Cambridge: Cambridge University Press.