The Battle of Coral Sea - May 4-8, 1942

The Battle of the Coral Sea was the first fleet action in which aircraft carriers engaged each other. While the Japanese considered it to be a tactical victory because of the sinking of the carrier Lexington, the battle was a strategic victory for the Allies as the Japanese abandoned their attempt to land troops to take Port Moresby, New Guinea. The engagement ended with no clear winner, but the damage suffered and experience gained by both sides set the stage for the Battle of Midway one month later.

In early 1942, having conquered nearly all of Southeast Asia in just a few months, Imperial Japan was at the height of its power. Still reeling from a long series of humiliating defeats, the Allies were just beginning to develop the skills and gather the resources needed to survive, stem the tide of Japanese successes and eventually roll back their territorial gains. Allied strategy at this time was focused on a defensive buildup of the United States Army and Marine strength on New Caledonia (well to the south of the Solomon Islands), and Australian Army and Royal Australian Air Force units in the south and east of the Australian Territory of New Guinea, just north of Australia.

On March 12, the Prime Minister of Japan, General Hideki Tōjō, said:
Australia and New Zealand are now threatened by the might of the Imperial forces, and both them should know that any resistance is futile. If the Australian government does not modify her present attitude, their continent will suffer the same fate as the Dutch East Indies.

In April 1942, Japanese forces left their new stronghold of Rabaul and launched a two-pronged attack: 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.

Three Japanese fleets 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 that Japanese land-based aircraft were being moved south and an operation was impending. To oppose it, there 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 would arrive too late to take part in the battle.

Lexington joined Yorktown on May 1. The Japanese occupied Tulagi without incident on May 3, and construction of a seaplane base began. After fueling, Yorktown closed on Tulagi and, on May 4, launched three successful strikes against Japanese shipping and aircraft there—revealing the presence of the carrier, but sinking the destroyer Kikuzuki and five merchant ships, crippling the island's seaplane reconnaissance capability, and damaging other vessels, before retiring to the south to rendezvous with the Lexington and the newly-arrived cruisers.

Land-based B-17s attacked the approaching Port Moresby invasion fleet on May 6, with the usual lack of success. Almost another year would pass before the USAAF realized that high-level bombing raids against moving naval targets were pointless. Although both carrier fleets flew extensive searches on the 6th, cloudy weather kept them hidden from each other, and the two fleets spent the night only 70 miles apart. Other Allied aircraft joined the battle, from airbases at Cooktown and Mareeba on Cape York Peninsula, Australia.

That night, Fletcher, mindful his primary role was to protect Port Moresby, made the difficult decision to detach his main surface force, Task Force 44 under Australian Rear Admiral John Gregory Crace, to block the probable course of an invasion. Crace had the cruisers HMAS Australia, HMAS Hobart, and USS Chicago, and the destroyers USS Perkins, USS Walke, and USS Farragut. Fletcher and Crace knew 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. Whether due to luck or skill, 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.

On the 7th, both fleets launched all available aircraft, but neither found the main body of the other, mistakenly attacking subsidiary enemy forces instead. Japanese aircraft found and attacked the U.S. fleet oiler Neosho and her escorting destroyer Sims, mistaking them for a carrier and a cruiser. Sims was sunk and Neosho crippled. Meanwhile, U.S. aircraft 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 ship in return. Shōhō was small by carrier standards, but the laconic phrase “scratch one flattop,” radioed back to the Lexington, announced the first Allied naval success of the Pacific War.

Finally, with dawn searches on May 8, the main carrier forces located one another and launched maximum effort raids, which passed each other in the air. Hidden by rain, Zuikaku escaped detection, but Shōkaku was hit three times by bombs. Listing and on fire, Shōkaku was unable to land her aircraft and was thus effectively put out of action. 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 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.

In tactical terms, the Japanese had achieved a narrow victory: one small carrier lost and a large carrier severely damaged against the Americans’ loss of a large carrier and significant damage to another. But from the Allied point of view, after five months of continuous defeat, a battle that came out almost even was close enough to a victory as not to matter.

In strategic terms, the Allies had won, as the seaborne invasion of Port Moresby was averted. Port Moresby was vital to Allied strategy, and could not have been defended by the ground forces then stationed there. This was the first time that a Japanese invasion force had been turned back without achieving its objective. It had a substantial effect on the morale and the strategic planning of both sides. Without a toehold in New Guinea, the subsequent Allied advance, difficult though it was, would have been much harder still. As a result, the Japanese were forced 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.

Overall, both Japanese fleet carriers survived, but both were not ready in time to participate at the decisive Battle of Midway, leaving them with four carriers to face the Americans. The US had permanently lost a carrier, but quick repairs to another meant that they had three carriers to take to battle. Essentially, Coral Sea helped to bring the Americans up to parity with the Japanese.
Although Zuikaku was only slightly damaged, with only 40 aircraft left, she was in no condition to fight, and had to return to Japan to replenish her air wings. Shōkaku was severely damaged, unable to operate aircraft, and took six months to repair. Neither carrier was able to take part in the decisive Battle of Midway. Despite the likely availability of sufficient aircraft between the two ships to re-equip Zuikaku with a composite air group, the Japanese made no serious attempt to get her to Midway. [3]
The loss of the Lexington was a severe blow, but in time, the U.S. was able to replace the ship, aircraft, and trained crew with others, superior in all respects. The damage to Yorktown was estimated to require months in port, but she could still operate aircraft, and she was made more-or-less battle-worthy in a miracle of improvisation after just two days in Pearl Harbor. It was thus able to play a vital part in one of the most important battles of the Pacific war: Midway. It would be her final battle; importantly, in that battle, she attracted torpedo assaults that might have otherwise gone to the undamaged Hornet and Enterprise.

The U.S. Navy learned a great deal from the Battle of the Coral Sea. From the loss of the Lexington, it realized that better ways were needed to contain aviation fuel and control defensive fighter aircraft. From the attacks on the Japanese carriers, coordination of dive-bombers and torpedo bombers had to be improved (though this hard-won knowledge came too late for the Battle of Midway). Most importantly of all, it was a significant morale boost as it showed that the Japanese could be beaten.
While Admiral Fletcher continued to command carrier forces and served as the senior USN officer at Midway, his opposite number, Admiral Takagi, was relegated to less important assignments in the aftermath of Coral Sea.