Answer:
Midway: The U.S. Navy was prepared for the attack - Admiral Nimitz was able to deduce quite accurately the size of the Japanese fleet, as well as their intentions. As a result, they were able to inflict devastating losses - Japan committed four aircraft carriers, with 248 aircraft on them to the battle, and lost all of them. The battle forced the Japanese to assume a defensive position, fighting battles that were incrementally closer to the Japanese homeland, and they lacked the resources to stage a large scale counter-offensive that would have repelled the U.S. forces.
Stalingrad: The Soviet forces held defensive positions in the city as German divisions surrounded them. While the Soviets were able to effectively defend, the Russian winter began to set in and the Germans continued to play offensively. Hitler was determined to not surrender so he tried to flank the Soviets but because they were so attritiated from loss of ammo and food, the Soviets easily defeated them and surrounded their forces. Soon after, the German forces in Stalingrad surrendered.