Battle Of The Coral Sea

In April 1942, Japanese forces left their stronghold of Rabaul (on New Britain, just north of New Guinea) and launched a two-pronged amphibious invasion of Port Moresby (Operation MO), and Tulagi in the Solomon Islands. The intention was threefold: to establish control of the Solomons, initially with a seaplane base; to destroy and then occupy Port Morseby (the last Allied base between Japan and Australia); and in doing these things, to 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 that they planned to greatly strengthen their hold on the Solomon Islands as a bastion against any future US counter attacks, a reasonable probability that northern Australia would be invaded, and considerable doubt about the following moves, if any. In practice, Japanese military planning structure was complex, had ill-defined areas of responsibility, and was crippled by endless bitter debates between army and navy. The only firm deduction that can be made about longer-term Japanese plans in the South Pacific is that whatever the navy eventually put forward would be opposed by the army with a counter-plan!

Three Japanese fleets set sail: the invasion forces for the Solomons and Port Moresby, and a covering force consisting of two big new aircraft carriers (Shokaku and Zuikaku, both Pearl Harbor veterans), a smaller carrier (Shoho), two heavy cruisers, and supporting craft. Alerted by radio intercepts, the Allies knew that Japanese land-based aircraft were being moved south and that an operation was impending. In opposition, they had three main fleets: USS Yorktown (CV-5) already in the Coral Sea under the command of Admiral Frank Jack Fletcher, USS Lexington (CV-2) en route, and a joint Allied surface fleet. The carriers USS Hornet (CV-8) and USS Enterprise (CV-6) were heading south after the Doolittle Raid on Tokyo but arrived too late to take part in the battle.

Land-based B-17s attacked the gradually approaching Port Moresby invasion fleet on May 6 with the usual lack of success. (Almost another year would pass before air forces realised that high-level bombing raids on 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.

On the 7th, both fleets flew off all available aircraft, but neither found the main body of the other, and both mistakenly attacked subsidiary forces. Japanese aircraft found the US fleet oiler USS Neosho (AO-23) and escorting destroyer USS Sims (DD-409); mistaking them for a carrier and a cruiser, they attacked and sank both. Meanwhile, the US aircraft had missed Shokaku and Zuikaku but found the invasion fleet, in company with the small carrier Shoho, which was soon sunk. In the previous five months, the Allies had lost a dozen battleships and carriers and been unable to sink a single major Japanese unit in return. Shoho was small by carrier standards, but the laconic "scratch one flattop" radioed back to Lexington brought news of the first Allied naval success of the Pacific war.

That night Fletcher, mindful that his primary role was to protect Port Moresby, took the tough decision to detach his surface fleet (cruisers HMAS Australia, USS Chicago (CA-29), HMAS Hobart, and two American destroyers) to block the progress of the invasion fleet toward Port Moresby, knowing that exposing surface ships to attack by land-based aircraft without air cover was to risk the same fate that had overtaken British battleships HMS Prince of Wales and HMS Repulse five months before.

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 Shokaku was hit three times by bombs. Listing and on fire, Shokaku was unable to land her aircraft and effectively out of action.

Both American carriers were hit by the Japanese strike: Yorktown by a bomb, the larger, less manoeuvrable Lexington by both bombs and torpedoes. Although she 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 torpedoed to prevent capture.

While the carrier task forces were battling, the Allied surface force had approached within range of land-based aircraft from Rabaul. It was attacked repeatedly through the day by Japanese bombers and once (mistakenly) by American B-17s, but survived intact and continued to stand between the invasion force and Port Moresby. Misled as to the strength of the surface force by returning fliers' reports, Japanese Admiral Inouye (in overall command of the operation from Rabaul) ordered the invasion fleet to return. With Shokaku damaged and Zuikaku short on aircraft, neither was able to take part in the crucial Battle of Midway a month later. Yorktown returned to Pearl Harbor.

• In tactical terms, the Japanese had had a narrow victory: one small carrier lost and a large carrier damaged, against the loss of a large carrier and equivalent 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.
• The seabourne invasion of Port Moresby was averted. Moresby was vital to Allied strategy, and could not have been defended by the ground forces then stationed there. The loss of Port Moresby may well have meant the loss of Australia, and would certainly have been a dreadful blow to the Allied cause. Without a toehold in New Guinea, the subsequent Allied advance, difficult though it was, would have been much harder still. As a result of the Coral Sea battle, the Japanese were forced to attempt taking Moresby overland. The consequent delay was just long enough to permit the arrival of veteran AIF soldiers to fight the Kokoda Track campaign, which in turn relieved pressure on Guadalcanal.
• The US Navy learned a great deal from the Battle of the Coral Sea. From the loss of Lexington the Navy learned better ways to contain aviation fuel and control defensive fighter aircraft, from the attacks on the Japanese carriers it learned more about coordination of dive-bombers and torpedo bombers to best effect (too late to help with Midway, but of value longer-term), and, perhaps most importantly of all, it learned that the Japanese could perhaps be beaten.
• The loss of Lexington was a severe blow, but in time the US was able to replace ship, aircraft, and pilots with others superior in all respects.
• The damage to Yorktown was estimated to require months in port, but in a miracle of improvisation she was made more-or-less battleworthy after just three days in Pearl, and was then able to play a vital part in the most important battle of the Pacific war: Midway.
• 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. Shokaku took six months to repair. Neither carrier was able to take part in the crucial battle of Midway - a very close-fought encounter that either carrier may have been able to turn.
• Less directly but no less significantly, the loss of highly trained aircrew from the carriers was never to be made up. Prior to the battles of the Coral Sea and (even more so) Midway, Japanese naval aviation was unchallengeable in two oceans. Long years of hard peace-time training, and real-life exercises against the hapless Chinese (and the scarcely less hapless western Allies) had honed an elite group of flyers. Japan could manufacture plenty of replacement aircraft, and at least a few replacement carriers, but could not replace the most skilled naval pilots in the world. From this time on, Japanese naval aviation began to decline.

References

Order of Battle

Japanese Forces

• Carrier Striking Force - Vice Admiral Takeo Takagi
  • Shokaku
  • Zuikaku
  • Myoko
  • Kaguro
  • destroyers (div 7) Ushio, Akebono
  • destroyers (div 27) Ariake, Yogure, Shiratsuyu, Shigure
  • oiler Toho Maru
• Tulagi Invasion Group - Rear Admiral Kiyohide Shima
  • minelayers Okinoshima (sunk), Koei Maru
  • transport Azumasan Maru
  • destroyers Kikuzuki (sunk), Yuzuki
  • (need smaller vessels)
• Port Moresby Invasion Group - Rear Admiral Sadamichi Kajioka
  • Yubari
  • destroyers Oite, Asanagi, Uzuki, Mutsuki, Mochizuki, Yayoi
  • Transport Unit - Rear Admiral Koso Abe
• Support Group - Rear Admiral Kuninori Marumo
  • Tenryu
  • Tatsuta
  • Kamikawa Maru
  • gunboats Keijo Maru, Seikai Maru, Nikkai Maru
• Covering Group - Rear Admiral Goto
  • Aoba
  • Kako
  • Kinugasa
  • Furutaka
  • Shoho (sunk)
  • Sazanami
• Submarine Force - Captain Noburu Ishizaki

Allied Forces

• Task Group 17.2 (Attack Group) - Rear Admiral Thomas C. Kinkaid
  • Minneapolis
  • New Orleans
  • Astoria
  • Chester
  • Portland
  • destroyer screen Phelps, Dewey, Farragut, Aylwin, Monaghan
• Task Group 17.3 (Support Group) - Rear Admiral J. G. Crace RN
  • Australia
  • Chicago
  • Hobart
  • destroyer screen Perkins, Walke
• Task Group 17.5 (Carrier Group) - Rear Admiral Aubery Fitch
  • Yorktown (CV-5)
  • Lexington (CV-2) (sunk)
  • destroyer screen Morris, Anderson, Hammann, Russell
• Task Group 17.6 (Fueling Group) - Captain John S. Phillips
  • Neosho (sunk)
  • Tippecanoe
  • destroyers Sims (sunk), Worden
• Task Group 17.9 (Search Group) - Commander George H. DeBaun
  • Tangier
    • VP-71 and VP-72: 12 PBY-5 Catalinas