The Battle of the Coral Sea, fought from May 4 – May 8, 1942, with most of the action occurring on May 7 and May 8, was a major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and the United States and Australia. It was the first fleet action in which aircraft carriers engaged each other. It was also the first naval battle in history in which neither side's ships sighted or fired directly upon the other.
It is considered a tactical victory for Japan, since the United States lost fleet carrier USS Lexington in exchange for the light carrier Shōhō. At the same time, the battle was a strategic victory for the Allies because the Japanese abandoned their attempt to land troops to take Port Moresby, New Guinea. The engagement ended with no clear victor, but the damage suffered and experience gained by both sides set the stage for the Battle of Midway.
In April 1942, Japanese forces left their new stronghold of Rabaul (on New Britain, just north of New Guinea), and launched a two-pronged strategy: an amphibious assault against Port Moresby (Operation “MO”), and another against Tulagi in the Solomon Islands. The intent was threefold: to establish control of the Solomons, initially with a seaplane base; to occupy Port Moresby (the last Allied base between Japan and Australia); and in so doing, bring the American aircraft carrier fleet to battle for the first time in the war.
Historians remain divided about Japanese longer-term intentions. There seems little doubt Japan planned to greatly strengthen its hold on the Solomon Islands as a bastion against any future U.S. counterattacks and may have intended to later occupy other island groups in the South Pacific in order to cut Australia off from the United States. However, an invasion of Australia was not planned at any time, nor within Japan's capabilities in any case. In practice, Japanese military planning was a complex process, with ill-defined areas of responsibility and that was crippled by endless, bitter debates between the Imperial Army and Navy. Regarding longer-range Japanese aims in the South Pacific, there was only one certainty - whatever strategy the navy put forward would be challenged by an army counterplan.
Three Japanese task forces set sail: the invasion forces for the Solomons and Port Moresby, and a covering force of two large modern aircraft carriers, Shōkaku and Zuikaku (both veterans of the attack on Pearl Harbor), a smaller carrier, Shōhō, two heavy cruisers, and supporting craft. Alerted by radio intercepts, the Allies knew Japanese land-based aircraft were being moved south and that an operation was impending. To oppose it were three main groups: Yorktown already in the Coral Sea under the command of Admiral Frank Jack Fletcher, with Lexington en route, and a joint Allied surface force. The carriers Hornet and Enterprise were heading south after the Doolittle Raid on Tokyo, but they arrived too late to take part in the battle.
That night, Fletcher, whose role was to protect Port Moresby, made the difficult decision to detach his main surface force, Task Force 44 under Australian Rear Admiral John Crace, to block the probable course of an invasion. Crace had the cruisers HMAS Australia, HMAS Hobart, and USS Chicago, and destroyers USS Perkins, USS Walke, and USS Farragut. Fletcher and Crace knew that exposing surface ships to attack by land-based aircraft, without air cover, risked a repeat of the loss of HMS Prince of Wales and HMS Repulse five months before. Their fears were nearly realized when the cruisers were spotted and came under an intense air attack from a squadron of torpedo bombers on the afternoon of May 7. The ships escaped with few casualties and little damage. Only minutes after the Japanese raid, Crace's force was inadvertently attacked by friendly B-17s; Farragut and Perkins once again had to endure near misses.
Meanwhile, U.S. aircraft, sent in the wrong direction by a miscoded contact report, had missed Shōkaku and Zuikaku but found the invasion fleet, escorted by the small carrier Shōhō, which was soon sunk with heavy casualties. In the previous five months, the Allies had lost numerous major warships and had been unable to sink a single major Japanese combatant in return. Shōhō was small by carrier standards, but the laconic phrase “scratch one flattop,” radioed back to Lexington by then-Lieutenant Commander Robert E. Dixon, announced the first Allied naval success of the Pacific War. Dixon's phrase was quoted by Chicago Tribune war correspondent Stanley Johnston in a June 1942 article and subsequently requoted in most accounts of the Pacific War. Lexingtons commanding officer, Captain Frederick C. Sherman, USN, credited Dixon with coining the word "flattop" which became standard slang for an aircraft carrier.
Lexingtons CXAM-1 RADAR detected the incoming Japanese aircraft at a range of 68 miles, but the Americans underestimated the performance of the Nakajima B5N and positioned fighters too low to intercept. Both American carriers were hit: Yorktown by a bomb; the larger, less maneuverable Lexington, by both bombs and torpedoes. Although the latter survived the immediate damage and was thought to be repairable, leaking aviation fuel exploded a little over an hour later. Lexington had to be abandoned and scuttled to prevent her capture.
Crace continued to stand between the invasion force and Port Moresby. Inoue was misled by returning fliers’ reports as to the strength of the Allied cruiser and destroyer force, and he recalled the invasion fleet. With Shōkaku damaged and Zuikaku short of aircraft, neither was able to take part in the crucial Battle of Midway a month later. The damaged Yorktown returned to Pearl Harbor.
It had a substantial effect on the morale and the strategic planning of both sides. Without a hold in New Guinea, the subsequent Allied advance, difficult though it was, would have been much harder still. As a result, the Japanese chose instead to attack Moresby overland. The consequent delay was just long enough to permit the arrival of the veteran Second Australian Imperial Force to fight the Kokoda Track campaign and the Battle of Milne Bay, which in turn relieved pressure on U.S. forces at Guadalcanal.
The loss of Lexington was a severe blow, as she was one of the Navy's largest carriers. Yorktown was able to still operate aircraft, and though her damage was estimated to require months in port, she was rushed to Pearl Harbor and made more or less battle-worthy in a miracle of improvisation and determination after just two days in drydock.