1) Battle of Midway, 1942 - US carriers ambushed the Japanese carrier force sent to attack Midway, sinking four carriers (the offensive backbone of the naval force sent) and losing only one (three US carriers were involved). It crippled the IJN and forced the Japanese onto the defensive.
2) Battle of Stalingrad, 1942 - 43 - The German Sixth Army was encircled and trapped by the Red Army and eventually surrendered when it was near starvation and almost out of ammunition. It destroyed the central spearhead of Hitler's offensive and pushed the Germans onto the defensive.
3) Second battle of El-Alamein, late 1942 - General Montgomery decisively defeated the Germans (led by the "Desert Fox", Erwin Rommel) at El-Alamein sealing the fate of the Afrika Corps and Italian ambitions for North Africa in retreat.
