The Japanese attack on Midway, which also included a feint to Alaska by a smaller fleet, was a ploy by the Japanese to lure the American carrier fleet into a trap. The Japanese hoped to avenge the bombing of the Japanese home islands two months earlier during the Doolittle Raid (an air raid on Tokyo), plug the hole in their Eastern defensive perimeter formed by U.S. control of Midway, finish off the U.S. Pacific Fleet, and perhaps even take Hawaii. Had the Japanese achieved their objective at Midway, the northeastern Pacific Rim would have been essentially defenseless against the Japanese Navy, since the remaining U.S. naval ships were fully deployed halfway around the world in the North Atlantic.

The Battle
Admiral Chuichi Nagumo launched his initial air attacks at dawn on June 4; Japanese carrier aircraft bombed and heavily damaged the U.S. base on Midway. American long-range bombers based on Midway, including B-17s, made several attacks on the Japanese, with little effect, and Midway-based fighter pilots, many flying outmatched obsolete Brewster Buffalos, made a heroic defense of Midway. These efforts by Midway-based aircraft led the Japanese strike leader to signal Nagumo that another strike would be necessary to neutralize the defenses, before the landing task force (proceeding independently from the southwest) could land ground troops and begin its assault.

Receiving this signal, Nagumo directed that his on-deck reserve planes (armed with anti-ship torpedo munitions, in case American ships were sighted) be taken below, to be re-armed with general purpose contact bombs, more appropriate for use on land targets. But, partially through this process, a scout plane from the cruiser Tone, which had been delayed 30 minutes due to catapult problems, signalled the discovery of a sizable American naval force to the east.

Nagumo now had half his reserve force armed with contact bombs (which would be useless in an attack on armored ships), and the initial strike winging back for its return. The admiral made the fateful decision to wait for his first strike force to land, then properly remount his forces for an overwhelming strike on the newly-sighted enemy ships, even though Admiral Tamon Yamaguchi, leading Carrier Division 2 (Hiryu and Soryu) and considered the heir to Admiral Yamamoto, signalled to Nagumo that he recommended striking immediately with the forces at hand.

With fuel hoses snaking across their hangar decks as refuelling operations were hastily completed, the Japanese carriers were at their most vulnerable. Adding to their peril, the change from torpedoes to bombs and back again resulted in volatile munitions being simply stacked on the deck and not returned and stowed safely in the magazines.

With Fletcher in overall command from Yorktown, but led by Spruance in Enterprise, who had better knowledge of the present operational situation, U.S. carrier forces had the advantage of knowing, through decryption of Japanese Navy communications, the enemy plans and intentions. Spruance had launched a pre-emptive attack from his carriers Enterprise and Hornet against the Japanese carriers. Anti-aircraft fire and fighters shot down 35 out of 41 TBD Devastator torpedo bombers, including every plane of Hornet's Torpedo Squadron 8 (see also George Gay). These slow and vulnerable torpedo-bombers had gotten separated from the other American carrier planes, including their protective fighter screen, and were thus attacking unescorted, and barely above sea level.

Land-based planes from Midway had also attacked the Japanese fleet, including six TBF Avengers in their first combat operation (five were shot down), B-26 Marauders, and high-flying B-17 Flying Fortresses. The Japanese shrugged off eight separate aerial attacks with almost no losses or battle damage.

The only hope the Americans had were with their dive bombers, of which squadrons from the three US carriers were in the air. Some pilots had lost their bombs, however, after testing new electric arming switches over the ocean, and the dive bomber pilots had not been given accurate directions to the Japanese fleet. Acting on a hunch and using dead reckoning, Commander Wade McClusky managed to bring his SBD Dauntless dive-bombers from the Enterprise over the Japanese fleet just as refuelling had completed and aircraft for the second strike were about to take off.

The eight earlier attacks had brought the defending Zeros fighter planes down low, almost to sea level. A cascade of lucky breaks had given the US dive bombers a clear run at their targets, devoid of air cover and covered with aviation fuel and stacked ordnance. In the incredible space of six minutes, the SBD's made their attack runs and left three of the Japanese carriers—Akagi, Kaga and Soryu— ablaze from stem to stern, scoring multiple dive-bomb hits. All three carriers would be abandoned and sunk. The core cadre of elite Japanese pilots, painstakingly well-trained in the pre-war years, and responsible for much of the Japanese success of the first six months of the war in the Pacific, were killed or incapacitated, while still on the decks of their carriers.

During the events of the morning, Hiryu had become separated from the three other now-sinking carriers. Undamaged, this carrier was able to launch a small strike on Yorktown, which was severely damaged. The Yorktown was able to survive both this and a second attack, only to be sunk during salvage efforts by torpedoes from a Japanese submarine on June 7. The same torpedo salvo sank the destroyer Hammann, which had been assigned to remain with Yorktown. With Yorktown damaged and abandoned, full command of the battle—and ultimate credit for its victory—passed from Admiral Fletcher, into the hands of Admiral Spruance. Aircraft from Enterprise in turn attacked Hiryu and set her ablaze, and damaged the destroyer Isokaze.

As darkness fell, both sides took stock, and made tentative action plans. Yamamoto initially decided to continue the effort, and sent a cruiser raiding force to bombard the island that night. Having lost four carriers, which were both the heart of the Imperial Japanese Navy and the air cover for his surface forces, however; he changed his mind and recalled the force.

Spruance, in tactical command, decided to maintain his position off Midway, close enough to intercept any Japanese moves toward the island, but maintaining enough distance so as to not run into a night action with the more powerful Japanese gunnery forces still in the area.

While beating its retreat in close column at night, the Japanese cruiser Mogami failed to adjust its course correctly for a column turn, and rammed the port quarter of the cruiser Mikuma. The following morning, Spruance's scout planes discovered the two crippled cruisers, and Spruance launched a strike. Mikuma was sent to the bottom, while Mogami managed to successfully fend off the bombers, and live to fight another day.

Aftermath
Having scored a decisive victory, American forces retired. The loss of four fleet carriers—leaving only Zuikaku and Shokaku—stopped the expansion of the Japanese Empire in the Pacific, and put Japan on the defensive. What made it a turning point for the Japanese Navy was that they lost their dominating force of large numbers of carriers with well-trained pilots, and from this, the Japanese would never recover. It had been six months to the day since the attack on Pearl Harbor. Admiral Yamamoto had predicted to his superiors that Japan would prevail for only six months to a year against the United States, after which American resources would begin to overwhelm the Japanese Navy. He had been exactly correct. American industrial output was greater than the combined Japanese and German industrial output. Nonetheless American victory was never inevitable; only probable.