Battle of Britain - Radar
Midway - Aircraft Carriers
Major battles that changed modern warfare
Battle of Trafalgar 1805
Significant as Midway was in the course of WWII, it was the Battle of Coral Sea (IIRC) which established the pre-eminence of the aircraft carrier. It was, I believe the first naval engagement in history in which enemy surface vessels never came in sight of each other. Midway followed shortly thereafter, but in the big picture, was as much a victory of naval intelligence as it was the carrier forces that dealt the death blows.