Battle of the Coral Sea | World War II

From 4 to 8 May 1942, the Action of the Coral Sea was a main naval combat between the Imperial Japanese Navy (IJN) and US and Australian naval and air forces. The combat, which took place in World War II's Pacific Theater, is historically noteworthy as the first action in which aircraft carriers attacked each other and the first in which the opposing ships did not sight or fire directly at one another. The Japanese invaded Port Moresby (New Guinea) and Tulagi to bolster their defensive posture in the South Pacific (in the southeastern Solomon Islands). Several necessary units of Japan's Combined Fleet were involved in Operation Mo. Under the overall leadership of Admiral Shigeyoshi Inoue, they included two fleet carriers and a light carrier to provide air cover for the invading forces. Through signals intelligence, the US learnt of the Japanese plan. As a result, they dispatched two US Navy carrier task forces and a joint Australian-American cruiser force to counter the operation under the overall direction of US Admiral Frank J. Fletcher.

Even though some of their supporting cruisers were sunk or damaged in surprise strikes by aircraft from the US fleet carrier Yorktown on 3–4 May, Japanese forces successfully assaulted and seized Tulagi. The Japanese fleet carriers headed towards the Coral Sea after learning of the existence of enemy carriers in the area to discover and destroy the Allied naval forces. Unbeknownst to anyone, the two carrier forces came within 70 nautical miles (81 miles; 130 kilometres) of one other on the evening of May 6th. Both sides began airstrikes on the 7th of May. Unfortunately, both sides mistookly assumed they were hitting their opponent's fleet carriers when attacking other units, with the Americans sinking the Japanese light carrier Shh and the Japanese sinking a US destroyer and severely injuring a fleet oiler, which was eventually dropped. Each side found and invaded the other's fleet carriers the next day. The Japanese fleet carrier Shkaku was damaged, the US fleet ship Lexington was severely damaged and ultimately scuttled, and the US fleet carrier Yorktown was damaged. The two forces disengaged and departed from the area after both sides incurred substantial losses in aircraft and carriers damaged or lost. Inoue recalled the Port Moresby invasion fleet due to the loss of carrier air cover, intending to try again later.

Although the combat was a Japanese triumph in terms of ships sunk, it was a strategic victory for the Allies in other aspects. The engagement marked the Allies' first time holding back a significant Japanese advance since the war began. More importantly, the Japanese fleet carriers Shkaku and Zuikaku, both damaged and with a depleted aircraft complement, could not participate in the Battle of Midway the following month. Still, Yorktown did so on the Allied side, ensuring a rough parity in aircraft between the opponents and contributing significantly to the US victory. The Japanese were unable to re-invade Port Moresby by sea after suffering heavy losses in carriers at Midway, which prompted their ill-fated land offensive via the Kokoda Track. The Allies launched the Guadalcanal Campaign two months later, taking advantage of Japan's strategic vulnerability in the South Pacific. That, together with the New Guinea Campaign, helped to break down Japanese fortifications in the South Pacific, paving the way for Japan's surrender and the conclusion of World War II.

Expansion of Japan

After Japanese forces attacked Malaya, Singapore, and Hong Kong, as well as the US naval base at Pearl Harbor, Japan declared war on the United States and the British Empire on December 8, 1941 (7 December US time). Japanese commanders hoped to weaken the US navy, conquer the natural resource-rich country, and secure critical military sites to defend their vast empire. The purposes of the initial Japanese campaigns in the impending war, according to Imperial Japanese Navy (IJN) Combined Fleet's "Secret Order Number One," on 1 November 1941, were to “American and British forte from the Netherlands Indies and the Philippines, to establish a policy of autonomous self-sufficiency and economic independence."

To achieve these goals, Japanese troops assaulted and effectively took control of the Singapore, Philippines, the Dutch East Indies, New Britain, Wake Island, the Gilbert Islands, and Guam during the first few months of 1942, inflicting tremendous losses on opposing Allied land, naval, and aviation forces. Japan intended to use these captured areas to construct a perimeter defence for its empire, from which it hoped to crush or exhaust any Allied counterattacks by attritional tactics.

Japan's Naval General Staff suggested an invasion of Northern Australia shortly after the war began to prevent Australia from being utilized as a base to threaten Japan's South Pacific perimeter defences. The Imperial Japanese Army (IJA) rejected the proposal, claiming that it lacked the necessary forces and maritime capability to carry out such an action. At the similar time, Vice Admiral Shigeyoshi Inoue, commander of the IJN's Fourth Fleet (also known as the South Seas Force), which included most of the South Pacific's naval units, backed for the profession of Tulagi in the southeastern Solomon Islands and Port Moresby in New Guinea, bringing Northern Australia inside range of Japanese land-based aircraft. Inoue believed that capturing and controlling these areas would provide the critical Japanese base in New Britain, Rabaul, more protection and defensive depth. The navy's general staff and the IJA supported Inoue's suggestion. In addition, they advocated for more operations to conquer New Caledonia, Fiji, and Samoa, cutting the supply and communication links between Australia and the United States by using these locations as staging areas.

The army and navy devised a plan known as Operation Mo in April 1942. According to the program, Port Moresby was to be invaded from the sea and captured by the 10th of May. On 2–3 May, the navy would seize Tulagi. It would set up a seaplane base for possible aviation operations against Allied territory and forces in the South Pacific and a base for reconnaissance planes. On 15 May, the navy planned to launch Operation RY, which would use ships released from Mo to take Nauru and Ocean Island for their phosphate reserves. Once Mo and RY were done, more operations against Fiji, Samoa, and New Caledonia (Operation FS) were prepared. Inoue requested that Japan's Combined Fleet send carriers to provide air protection for Mo following a deadly airstrike by Allied land- and carrier-based aircraft on Japanese naval forces attacking the Lae-Salamaua area in New Guinea March. Inoue was particularly concerned about Allied bombers deployed in Townsville and Cooktown, Australia, outside the range of his bombers based in Rabaul and Lae.

Commander-in-chief, Admiral Isoroku Yamamoto of the Combined Fleet, was planned an operation for June in the central Pacific around Midway Atoll in the hopes of luring the US Navy's carriers, none of which had been dented in the Pearl Harbor attack, into a decisive battle. Accordingly, Yamamoto dispatched some of his significant warships to support Mo, counting two fleet carriers, a cruiser division, a light carrier, and two destroyer divisions and put Inoue in charge of the naval side of the operation.

The Response of the Allies

Unbeknownst to the Japanese, the United States Navy, commanded by the Office of Naval Communications' Communication Security Section, had been successful in breaking Japanese communication ciphers and codes for several years. By March 1942, the United States had deciphered up to 15% of the IJN's Ro or Naval Codebook D code (dubbed "JN-25B" by the Americans), which was utilized for roughly half of the IJN's communications. By the end of April, the United States had decoded 85 per cent of the Ro code messages.

The United States initially became aware of the MO operation in intercepted messages in March 1942. The United States blocked an IJN telegram on April 5th directing a carrier and other heavy warships to Inoue's area of operations. On the 13th of April, the British decoded an IJN communication telling Inoue that the Fifth Carrier Division, which included the fleet carriers Shkaku and Zuikaku, was en route from Formosa to his command via the significant IJN base at Truk. The British relayed the message to the Americans and their assessment that MO would most certainly strike Port Moresby.

Admiral Chester W. Nimitz, the new commander-in-chief of US forces in the Central Pacific, studied the decrypted signals. They concluded that the Japanese planned a big offensive in the Southwest Pacific in early May, with Port Moresby as the likely objective. The Allies saw Port Moresby as a critical base for a planned counteroffensive against Japanese forces in the South-West Pacific, General Douglas MacArthur. According to Nimitz's staff, the Japanese strategy could include carrier raids on Allied bases in Samoa and Suva. After consulting with Admiral Ernest King, Commander in Chief of the US Fleet, Nimitz resolved to counter the Japanese effort by dispatching all four of the Pacific Fleet's aircraft carriers to the Coral Sea. By the 27th of April, additional signals intelligence corroborated most of the MO and RY plans' specifics and objectives.

Nimitz issued orders on April 29th to send his four carriers and accompanying forces to the Coral Sea. The carrier Yorktown, accompanied by three cruisers and four destroyer ships, and reinforced by a resupply group of two oilers and two destroyer ships, was by now in the South Pacific, having departed Tongatabu on April 27 on route to the Coral Sea. Between Fiji and New Caledonia, TF 11 was commanded by Rear Admiral Aubrey Fitch and consisted of the carrier Lexington, two cruisers, and five destroyers. Vice Admiral William F. Halsey's Task Force 16, which included the carriers Enterprise and Hornet, had recently returned from the Doolittle Raid in the central Pacific. TF 16 left right away, but it would not make it to the South Pacific in time to take part in the combat. Until Halsey arrived with TF 16, Nimitz placed Fletcher in command of Allied naval forces in the South Pacific. Even though the Coral Sea area was under MacArthur's control, Fletcher and Halsey were ordered to report to Nimitz rather than MacArthur while in the area.

The Japanese concluded that all but one of the US Navy's carriers were in the central Pacific based on intercepted radio traffic from TF 16 as it returned to Pearl Harbor. However, the Japanese had no idea where the remaining ship was, and they didn't expect a reaction from a US carrier until the operation was well underway.

Prelude

In late April, the Japanese submarines Ro-33 and Ro-34 reconnoitred the landing area. Aux Louisiade Archipelago, the submarines investigated Rossel Island, Deboyne Group, Jomard Channel, and the eastern approach to Port Moresby. They saw no Allied ships in the region and returned to Rabaul on April 23 and 24.

The Japanese Port Moresby Invasion Force had 11 transporting 5,000 IJA South Seas Detachment personnel and 500 3rd Kure Special Naval Landing Force troops (SNLF). The Port Moresby Attack Force, led by Rear Admiral Sadamichi Kajioka, escorted the transports. On May 4, Abe's ships left Rabaul towards Port Moresby, accompanied by Kajioka's troops the next day. The ships planned to transverse the Jomard Channel in the Louisiades to travel around the southern edge of New Guinea by May 10. With barely half being infantry and all being poorly supplied and trained, the Allied garrison at Port Moresby totalled around 5,333.

On the attack against Tulagi was the Tulagi Invasion Force, headed by Rear Admiral Kiyohide Shima. The Covering Group, led by Rear Admiral Aritomo Got, consisted of the light carrier Shh, four heavy cruisers, and one destroyer. The Cover Force (also known as the Support Group) was led by Rear Admiral Kuninori Marumo and comprised two light cruisers, the seaplane tender Kamikawa Maru, and three gunboats. Cover Force and Covering Group were to relocate once Tulagi was taken on 3 or 4 May. Inoue led the MO operation from the Kashima, which arrived from Truk on May 4.

It crossed the Solomons between Bougainville and Choiseul, then station near New Georgia Island. On 29 April, Marumo's support group left New Ireland for Thousand Ships Bay, Santa Isabel Island, to set up a sea aircraft base for the Tulagi attack on 2 May. Shima had invaded Rabaul.

Carriers Zuikaku and Shkaku led a strike force of two heavy cruisers and six destroyers from Truk on May 1. Vice Admiral Takeo Takagi (flag on cruiser Myk) led the strike force, with Rear Admiral Chichi Hara (flag on Zuikaku) leading the carrier air forces. Soleil's Carrier Strike Force planned to reach the Coral Sea south of Guadalcanal. From there, they were to provide air cover for the invading troops, destroy Allied air power over Port Moresby and intercept and destroy any Allied naval forces responding.

Takagi's carriers were to carry nine Zero fighters to Rabaul. Two attempts on 2–3 May were hampered by bad weather, and one of the Zeros had to ditch in the sea. Takagi had to abandon the delivery operation after the second attempt to stay to the MO timetable. A scouting line of Japanese submarines 450 mi (520 mi; 830 km) southwest of Guadalcanal was despatched to warn of any Allied naval forces approaching. Fletcher's parties had entered the Coral Sea area before the submarines arrived, so the Japanese were unaware. On May 2, Yorktown planes attacked I-21, a submarine assigned to scout around Nouméa. The submarine was unharmed and didn't understand it was being targeted by carrier aircraft. Ro-33 and Ro-34 were also deployed to blockade Port Moresby on May 5. Neither submarine engaged any ships.

It was around 560 km northwest of New Caledonia on May 1st when TF 17 and 11 merged. Aboard the Tippecanoe, Fletcher detached TF11 while TF 17 refuelled at Neosho. TF 17 finished refuelling the next day, although TF 11 reported spending on May 4. Fletcher instructed TF 11 to meet TF 44, en way from Sydney and Nouméa, on May 4th. TF 44 was commanded by MacArthur and comprised of the cruisers HMAS Australia, Hobart, USS Chicago, and three destroyers. Tippecanoe then left the Coral Sea to give Allied ships at Efate its remaining fuel.

Tulagi

To occupy Tulagi, Shima's men arrived early on May 3rd. Before Shima arrived, Tulagi's small force of Australian commandos and a Royal Australian Air Force reconnaissance unit had evacuated. Japan promptly began building a seaplane and communications base. Early afternoon, Got's force headed towards Bougainville to refuel in preparation for the landings at Port Moresby.

To Fletcher's surprise, the Japanese Tulagi invasion force had been seen reaching the southern Solomons the day before. Fletcher was unaware that TF 11 had refuelled ahead of schedule and was within 60 nmi (110 km) east of TF 17 but could not communicate due to Fletcher's orders to keep the radio-quiet. To conduct airstrikes against the Japanese soldiers at Tulagi the following day, TF 17 reversed direction and flew at 27 km (31 mph; 50 km/h).

From 100 nmi south of Guadalcanal, 60 TF 17 planes launched three successive strikes against Shima's forces off Tulagi on May 4. A surprise attack by Yorktown aircraft sank the destroyer Kikuzuki and three minesweepers, damaged four other ships, and destroyed four seaplanes assisting the landings. The US lost one torpedo bomber and two fighters, but all crews were rescued. TF 17 retired to the south late on May 4th after retrieving its aircraft. Tulagi began flying surveillance missions from Tulagi on May 6th, despite the damage caused by the carrier strikes.

On May 4, Takagi's Carrier Striking Force received word of Fletcher's strike while refuelling 350 nmi north of Tulagi. So Takagi stopped refuelling, flew southeast, and deployed scout planes to look east of the Solomons for US carriers. So the search planes discovered nothing.

Air Searches and Decisions

On May 5, at 08:16, TF 17 met up with TF 11 and TF 44 320 nmi (370 km) south of Guadalcanal. Around the same time, four Yorktown Grumman F4F Wildcat fighters intercepted and shot down a Kawanishi H6K reconnaissance flying boat from the 25th Air Flotilla based at the Shortland Islands. The plane didn't report before it crashed, so the Japanese concluded it was shot down by carrier planes. In a cable from Pearl Harbor, Fletcher learned that the Japanese planned to land soldiers at Port Moresby on May 10th and that their fleet carriers would likely be nearby. Armed with this knowledge, Fletcher ordered TF 17 to Neosho. After refuelling on May 6, he planned to march his soldiers north towards the Louisiades on May 7.

Overnight, Takagi's carrier force passed south of San Cristobal (Makira) and entered the Coral Sea after transiting Guadalcanal and Rennell Island on May 6. Takagi began refuelling his ships 180 nmi (210 mi; 330 km) west of Tulagi, anticipating a carrier engagement the next day. Fletcher merged TF 11 and 44 on May 6. Fletcher kept refuelling, thinking the Japanese carriers were still north near Bougainville. However, throughout the day, US carrier reconnaissance missions failed to detect any Japanese naval forces because they were beyond scouting range.

At 10:00, a Tulagi Kawanishi reconnaissance flying boat spotted TF 17. Takagi got the news at 10:50. Takagi's force was roughly 300 nmi (560 km) north of Fletcher. Takagi's ships were still refuelling and not ready for the fight. Grounded on the sighting report, TF 17 was moving south and expanding its range. A thick, low-hanging cloud made it impossible for Takagi and Hara's aircraft to locate Fletcher's ships. Takagi sent two carriers and two destroyers under Hara's command to TF 17 at 20 km (23 mph; 37 km/h) to strike at first light the next day while his other ships refuelled.

Invading forces, including Got's warships, were targeted multiple times on May 6 by US B-17 bombers based in Australia. MacArthur's headquarters radioed Fletcher about the attacks and the Japanese invasion forces' whereabouts. In addition, MacArthur's fliers reported seeing a carrier about 425 nmi (489 mi; 787 km) northwest of TF 17, adding to Fletcher's fleet carrier theory.

At 18:00, TF 17 finished fueling, and Fletcher detached Neosho with Sims to rendezvous further south (16°S 158°E). On the way to Rossel Island, TF 17 turned northwest. By 20:00 that night, their carriers were barely 70 nmi (130 km) apart. After refuelling, Hara changed course to meet Takagi around 20:00.

Kamikawa Maru established a seaplane base in the Deboyne Islands late on May 6 or early on May 7 to support the invading forces approaching Port Moresby. Marumo's Cover Force then positioned itself near the D'Entrecasteaux Islands to shield Abe's approaching convoy.

Carrier Battle, First Day

Morning Strikes: Rossel Island located 115 nmi south of TF 17 at 06:25 on May 7. Fletcher dispatched Crace's cruiser force, Task Group 17.3, to block the Jomard Passage. Fletcher knew Crace would be without air support as TF 17's ships searched for and attacked the Japanese carriers. Detaching Crace decreased Fletcher's anti-aircraft defences. Nonetheless, Fletcher believed the danger was required to prevent the Japanese invading forces from reaching Port Moresby.

Fletcher ordered Yorktown to launch 10 Douglas SBD Dauntless dive bombers as scouts north of Takagi's carrier force, near the Louisiades, at 06:19. Hara thought Fletcher was south of him and told Takagi to send the plane there. Takagi (13°12′S 158°05′E) launched 12 Nakajima B5Ns at 06:00 to scout for TF 17. While this was going on, Got sent four Kawanishi E7K2 Type 94 floatplanes southeast of the Louisiades. In addition, several Deboyne floatplanes, four Tulagi Kawanishi H6Ks, and three Rabaul Mitsubishi G4M bombers aided their hunt. Once the adversary was found, each side launched the balance of its carrier assault aircraft.

The US ships were 163 nmi (188 mi; 302 km) away from Takagi at 07:22, according to a Shkaku carrier scout. One cruiser, one carrier, and three destroyers, the scout reported at 07:45. A Shkaku scout plane confirmed the sighting. As a result, the oiler Neosho and destroyer Sims were sent away from the fleet to a southern rendezvous site. With Takagi's approval, Hara launched all his available aircraft after locating the US carriers. At 08:00, 78 aircraft (18 Zero fighters, 36 Aichi D3A dive bombers, and 24 torpedo planes) took off from Shkaku and Zuikaku, arriving at 08:15. Lieutenant Commander Kakuichi Takahashi led the strike force, while Lieutenant Commander Shigekazu Shimazaki led the torpedo bombers.

At 08:20, a Furutaka plane located Fletcher's carriers and quickly reported it to Inoue's Rabaul headquarters, which informed Takagi. A Kinugasa floatplane confirmed the sighting around 8:30. Confounded by the conflicting sighting reports, Takagi and Hara opted to keep attacking the ships to their south but move their carriers northwest to narrow the distance with Furutaka's claimed encounter. The contradicting information suggested to Takagi and Hara that the US carrier forces were split into two groups.

John L. Nielsen's Yorktown SBD saw Got's unit screening the invasion convoy at 08:15. Nielsen reported "two carriers and four heavy cruisers" at 225 nmi (259 mi; 417 km) northwest TF17. Fletcher ordered all available carrier aircraft to attack with the Japanese leading carrier group found. American strike of 93 aircraft (18 Grumman F4F Wildcats, 53 Douglas SBD Dauntless dive bombers, and 22 Douglas TBD Devastator torpedo bombers) arrived at 10:13. Once on land, Nielsen found his code problem. According to Nielsen, the main fleet consisted of two cruisers and four destroyers. In the 30 nmi (56 km) south of Nielsen's sighting, at 10°35′S 152°36′E, Fletcher reported an aircraft carrier, ten types of transport, and 16 warships. The B-17s saw Shh, Got's cruisers, and the Port Moresby Invasion Force. Fletcher directed the airborne strike group towards the main Japanese carrier force to the east.

Takahashi's strike group arrived at 09:15, sighted Neosho and Sims, and searched for hours for the US carriers. At 10:51, Shkaku scout pilots realized they had misidentified the oiler and destroyer as aircraft carriers. As a result, invasion forces were in grave danger because the US carriers stood between them and the invasion convoy. Torpedo bombers and fighters abandoned their operation at 11:15, while 36 dive bombers attacked the two US ships.

All eight dive bombers attacked Sims. Tri-bombed, the destroyer sank instantly, killing all but 14 of her 192-man crew. Seven bombs hit Neosho. A dive bomber injured by anti-aircraft fire collided with an oiler. Neosho (16°09′S 158°03′E) was severely damaged and powerless. However, she gave incorrect coordinates (16°25′S 157°31′E) for its location.

At 10:40, the US strike aircraft sighted Shh northeast of Misima Island and deployed to attack. Six Zeros and two Mitsubishi A5M fighters protected the Japanese carrier while the rest prepared below decks for a raid against the US carriers. Got's cruisers formed a diamond around the carrier, 3,000–5,000 yards (2,700–4,600 m) apart.

Lexington's air team, commanded by Commander William B. Ault, attacked first, destroying Shh with two 1,000 lb bombs and five torpedoes. To retaliate, Yorktown's air group dropped up to 11 more 1,000 lb (450 kg) bombs and two torpedoes on the blazing carrier at 11:00. Around 11:35 (10°29′S 152°55′E), Shh sunk. Withdrawing his warships to the north, Got dispatched the destroyer Sazanami back to rescue survivors. Of the 834 crew members, just 203 survived. Two SBDs from Lexington and one SBD from Yorktown were lost in the attack. Three CAP fighter pilots managed to ditch at Deboyne and survive. At 12:10, Lexington SBD pilot and squadron leader Robert E. Dixon radioed TF 17 to congratulate them on the mission's accomplishment "One flat top! Reply Bob"

Afternoon Operations: By 13:38, the US aircraft had returned to their carriers. They were rearmed and ready to attack the Port Moresby Invasion Force or Got's cruisers by 14:20. Fletcher was worried about the remaining Japanese fleet carriers' whereabouts. Allied intelligence sources suspected up to four Japanese carriers may be assisting the MO operation, he said. Fletcher decided that it was too late to attack when his scout planes spotted the remaining carriers. So Fletcher chose not to strike again today, hiding under the thick, overcast fighters ready to defend. Instead, Fletcher steered TF 17 SW.

After learning of Shh's loss, Inoue ordered the invasion convoy to go north and Takagi, positioned 225 nmi east of TF 17, to attack the US carrier forces. Eight US Army B-17s bombed the invasion caravan, but it was unharmed. Got and Kajioka were to prepare for a night surface fight south of Rossel Island if the US ships approached.

Crace's detached cruiser and destroyer force were detected at 12:40 p.m., 78 nmi (90 mi; 144 km) off Deboyne. At 13:15, a Rabaul aircraft observed Crace's staff but reported it had two carriers and was located 205°, 115 nmi (213 km) from Deboyne. Based on these reports, Takagi manoeuvred his carriers due west at 13:30 and informed Inoue at around 15:00 that the US carriers were at least 430 nmi west of his location and that he could not attack them that day.

Inoue's staff dispatched two attack aircraft groups from Rabaul towards Crace's reported position. The first group consisted of 12 G4M bombers armed with torpedoes, and the second 19 Mitsubishi G3M land assault aircraft. Both groups claimed to have sunk a "California-type" battleship and damaged another battleship and cruiser around 14:30. In actuality, Crace's ships unharmed four G4Ms. In addition, three US Army B-17s erroneously bombed Crace, causing minor damage.

He told Fletcher at 15:26 that he needed air support to finish his job. As the Japanese navy advanced beyond the Louisiades through the Jomard Passage or the China Strait, Crace retired to a position around 220 nmi (410 km) southeast of Port Moresby to enhance the range of Japanese carrier- or land-based aircraft. Unfortunately, Crace's ships were running low on gasoline, and he had no idea where Fletcher was or what he was up to.

After 15:00, Zuikaku received a message from a Deboyne reconnaissance plane saying Crace's unit had changed direction to 120° true (southeast). It was anticipated that the aircraft was following Fletcher's carriers and that if they kept that path, they would be within striking range before midnight. But Takagi and Hara were resolved to act promptly, even if it meant returning after dark.

At 15:15, Hara launched a reconnaissance flight of eight torpedo bombers to sweep 200 nmi (230 mi; 370 km) westward. The Neosho dive bombers returned and landed around the same time. Six tired dive bomber pilots were told they were going on another mission. At around 16:15, Hara launched 12 dive bombers and 15 torpedo planes with a heading of 277° to 280 nmi. The eight scout planes flew 200 nmi and returned without finding Fletcher's ships.

At 17:47, TF 17 identified the Japanese strike on radar headed towards them, turned southeast into the breeze, and vectored 11 CAP Wildcats led by Lieutenant Commanders Paul H. Ramsey and James H. Flatley to intercept. Surprising the Japanese formation, the Wildcats shot down seven torpedo bombers and one dive bomber, losing three Wildcats in the process.

After suffering substantial losses that dispersed their formations, the Japanese strike leaders halted the mission. The Japanese planes all ditched their weapons and turned back to their ships. 18:30. Several Japanese dive bombers encountered the US carriers in the darkness at 19:00 and circled in preparation for landing before being chased away by TF 17's destroyers. TF 17 and Takagi were around 100 nmi (120 km) distant by 20:00. Takagi used his warships' searchlights to help the 18 surviving planes home.

Between 15:18 and 17:18, Neosho radioed TF 17 that she was moving northwest and sinking. Unfortunately, Neosho's 17:18 report included incorrect coordinates, hindering US rescue efforts to find the oiler. Moreover, the news alerted Fletcher that his only tight gasoline supply was gone.

Fletcher ordered TF 17 west as dusk approached, preparing to commence a 360° search at first light. Crace went west to avoid the Louisiades. Inoue ordered Takagi to destroy the US carriers the next day, pushing the Port Moresby landings back to May 12. Takagi chose to take his carriers 120 nmi (140 mi; 220 km) north overnight to focus his morning exploration to the west and south and protect the invasion convoy. Unfortunately, Kajioka couldn't position and coordinate their ships in time to strike the Allied cruisers at night.

With their fatigued aircrews trying to catch a few hours of sleep, both sides prepared their strike aircraft for the impending conflict. "Without a hesitation, May 7, 1942, vicinity of Coral Sea, was the most chaotic fighting location in history," said US Vice Admiral H. S. Duckworth in 1972. Hara later said Yamamoto's chief of staff, Admiral Matome Ugaki, that he was frustrated by the "bad luck" the Japanese had on May 7.

Carrier Combat, Second Day

Attack on the Japanese Carriers: At 06:15 on May 8, Hara sent seven torpedo bombers to search the region bearing 140–230°, out to 250 nmi (290 km; 460 km) from the Japanese carriers. Three Tulagi Kawanishi H6Ks and four Rabaul G4M bombers assisted in the search. At 07:00, the carrier striking force moved southwest, joined by two Got cruisers, Kinugasa and Furutaka. The invasion convoy, Got, and Kajioka sailed towards a rendezvous spot 40 nmi (46 km) east of Woodlark Island. On May 7, a warm frontal zone with low clouds masked the US carriers and now blanketed the Japanese ships, limiting visibility to 2 to 15 nautical miles.

At around 06:35, TF 17 launched 18 SBDs to perform a 360° search to 200 nmi southeast of the Louisiades. The US carriers had a visibility of 17 nmi.

At 08:20, Joseph G. Smith, pilot of a Lexington SBD, sighted the Japanese carriers and reported TF 17. Kenz Kanno, piloting a Shkaku search plane, saw TF 17 and alerted Hara. However, 220 miles (390 kilometres) separated the two forces. Both sides rushed to fire strike planes.

At 09:15, commanded by Takahashi, the Japanese carriers launched a combined strike of 18 fighters, 33 dive bombers, and 18 torpedo planes. Each of the US carriers struck separately. By 09:15, Yorktown's group of six soldiers, 24 dive bombers, and nine torpedo planes had arrived. Torpedo squadron Lexington took out at 09:25. Both the US and Japanese carrier battleship groups moved directly towards each other to reduce the distance their planes had to fly on their return legs.

On the Japanese ships at 10:32, Yorktown's dive bombers waited to let the slower torpedo squadron approach to attack simultaneously. Zuikaku was covered beneath a rainstorm of low-hanging clouds as Shkaku arrived. 16 CAP Zero fighters guarded the two carriers. The Yorktown dive bombers attacked Shkaku at 10:57 a.m. with two 1,000 lb (450 kg) bombs, tearing apart the forecastle and damaging the carrier's flight and hangar decks. The Yorktown torpedo planes missed their targets. The strike downed two US dive bombers and two CAP Zeros.

Lexington's planes attacked around 11:30. Two dive bombers struck Shkaku, damaging it with a 1,000 lb (450 kilograms) bomb. Two more dive bombers attempted Zuikaku but missed. The rest of Lexington's dive bombers couldn't find the Japanese carriers. All 11 Lexington TBD torpedoes missed Shkaku. The 13 CAP Zeros downed three Wildcats on patrol. Shkaku could not fly due to a damaged flight deck, 223 crew members killed or injured, fuel storage tank explosions, and a devastating engine repair workshop. Her captain, Takatsugu Jjima, asked Takagi and Hara for permission to leave the combat, which Takagi granted. At 12:10, Shkaku retired with two destroyers to the northeast.

Raid on the U.S. Carriers: At around 10:55, Lexington's CXAM-1 radar detected the inbound Japanese aircraft at 68 nmi. Six Wildcats were stationed too low, expecting the Japanese torpedo bombers to be considerably lower than they were. The Japanese could not fully sink both carriers because of severe aircraft losses the night before. Lieutenant Commander Shigekazu Shimazaki sent 14 torpedo planes to Lexington and Yorktown. As the Japanese torpedo planes descended to assault position, a Wildcat shot down one and patrolling SBDs (15 from Lexington) knocked down three more. Responding Zeros downed four Yorktown SBDs. Survivor Vejtasa claimed three Zeros during the assault (though none were lost).

At 11:13 a.m., the carriers and their escorts started the fire with anti-aircraft guns. All four torpedo planes attacking Yorktown missed. The remaining torpedo planes hit Lexington with two Type 91 torpedoes at 11:20 a.m. It sank the port aviation gasoline tanks. Gasoline vapours escaped into adjacent compartments. Torpedo #2 broke the port water main, decreasing water pressure to the forward firerooms and causing the boilers to turn off. The ship's surviving boilers could make 24 kg (28 mph; 44 km/h). Anti-aircraft fire downed four Japanese torpedo planes.

The 33 Japanese dive bombers circled for three to four minutes before diving from 14,000 ft (4,300 m) to attack upwind. Takahashi's Shkaku dive bombers lined up on Lexington, while Tamotsu Ema's Shkaku dive bombers targeted Yorktown. Four Lexington CAP Wildcats tried to intervene, but two Wildcats circling above Yorktown could shatter Ema's formation. Takahashi's bombers hit Lexington twice and missed several times, creating fires put out by 12:33. At 11:27 a.m., a single 250 kg (550 lb) semi-armoured bomb pierced four decks before exploding, severely wrecking an aircraft storage room, killing or injuring 66 men, and damaging the superheater boilers. Up to 12 near misses damaged Yorktown's hull. A CAP Wildcat shot down two dive bombers during the attack.

As the Japanese aircraft finished their attacks and tried to escape, they came afoul of CAP Wildcats and SBDs. In the ensuing aerial battles, the Americans lost three SBDs and three Wildcats, while the Japanese lost three torpedo bombers, one dive bomber, and one Zero. By midnight, both US and Japanese strike groups had returned to their carriers. The two adversaries' aircraft flew over each other during their return, causing more air-to-air combat. Both Kanno and Takahashi's planes were shot down.

Recovery, Reassessment and Retreat: Between 12:50 and 14:30, the strike troops landed on their respective carriers, several damaged. Yorktown and Lexington both recovered aircraft from returning air units despite the damage. As part of the rescue effort, the US lost five SBDs, two TBDs, and a Wildcat, while the Japanese lost two Zeros, five dive bombers, and one torpedo plane. 46 of the 69 Japanese strike aircraft returned from the mission and landed on Zuikaku. Three more Zeros, four dive bombers, and five torpedo planes were deemed unsalvageable and were hurled into the water.

Aboard TF 17, Fletcher assessed the situation. The returning aviators reported seriously damaging one ship but barely damaging another. Fletcher wrote damage to both carriers and severe fighter losses in his air groups. Fuel was also an issue after losing Neosho. Radio intercepts backed up the reports of two intact Japanese carriers. Fitch informed Fletcher at 14:22. Fletcher withdrew TF17 from the action, believing the Japanese carriers outnumbered him. To target the Japanese carriers, Fletcher suggested MacArthur use his land-based bombers.

Around 14:30, Hara notified Takagi that the carriers only had 24 Zeros, eight dive bombers, and four torpedo planes. Takagi was concerned about his ships' fuel levels; his cruisers were at 50% and his destroyers at 20%. Takagi informed Inoue at 15:00 that his flyers had sunk two US carriers, Yorktown and a "Saratoga-class, to offer air support for the invasion." Inoue recalled the invasion convoy to Rabaul, postponed MO until July 3, and ordered his soldiers to concentrate northeast of the Solomons to begin the RY operation. In Rabaul, Zuikaku and her aides went, while Shkaku went to Japan.

At 12:47 a.m., sparks from unsupervised electric motors ignited gasoline vapours near Lexington's central control station. In the ensuing fire, 25 persons died. Around 14:42, a second massive explosion triggered a severe fire. At 15:25, a third explosion occurred, and the ship's crew reported unmanageable fires. Finally, at 17:07, Lexington's crew abandoned the ship. Following the rescue of the survivors, the destroyer Phelps launched five torpedoes into the blazing carrier, which sank in 2,400 fathoms at 19:52. Two hundred sixteen of the carrier's 2,951 crew members died and 36 aircraft. As soon as Phelps and the helping warships left, TF17 retired to the southwest, rejoining Yorktown and her escorts at 16:01. In the late evening, MacArthur notified Fletcher that eight of his B-17s had bombed the retreating invasion convoy.

Crace detached Hobart and the troubled destroyer Walke to Townsville that nightfall. In the Coral Sea, Crace stayed on patrol with the rest of TG17.3 if the Japanese invasion force resumed its march towards Port Moresby, as reported by radio.

On May 9, TF 17 changed direction to the east, exiting the Coral Sea south of New Caledonia. After refuelling at Tongatabu, Nimitz ordered Fletcher to return Yorktown to Pearl Harbor. However, Deboyne and Kamikawa Maru were assaulted by US Army bombers during the day. Meanwhile, Crace deduced that TF17 had left the area after not hearing from Fletcher. Hearing no further reports of Japanese ships approaching Port Moresby, Crace turned south towards Australia, arriving at Cid Harbor, 130 nmi (150 km) south of Townsville, on May 11.

On May 8, around 22:00, Yamamoto ordered Inoue to turn his forces around and destroy the remaining Allied battleships. Inoue ordered Takagi and Got to chase the remaining Allied vessel forces in the Coral Sea. Takagi's battleships spent most of May 9th replenishing the fleet oiler Th Maru. Takagi and Got sailed into the Coral Sea late on May 9. On May 10, Deboyne seaplanes helped Takagi hunt for TF 17. Unfortunately, Fletcher and Crace had already left the area. Takagi opted to return to Rabaul at 13:00 on May 10. Yamamoto agreed with Takagi and sent Zuikaku back to Japan to resupply her air groups. At the same time, Kamikawa Maru left Deboyne. One PBY on patrol from Nouméa saw the drifting Neosho about midday on May 11. Later that day, the US destroyer Henley rescued 109 Neosho and 14 Sims survivors before scuttling the tanker.

Operation RY began on May 10. The landings were postponed when the operation's flagship, minelayer Okinoshima, was sunk by the US submarine S-42 on May 12. To counter the Japanese approach to Nauru and Ocean Island, Halsey's TF 16 reached the South Pacific near Efate on May 13. On May 14, Nimitz instructed Halsey to ensure that Japanese scout aircraft observed his ships the next day and quickly returned to Pearl Harbor. Unknown TF 16 445nmi (824km) east of the Solomons was observed at 10:15 on May 15. The ruse worked. Because of this, Inoue cancelled RY and ordered his ships to return to Rabaul and Truk. On May 19, TF 16 departed Efate for Pearl Harbor, arriving on May 26. Yorktown arrived the next day.

Shkaku arrived in Kure on May 17th, nearly capsized in a storm owing to battle damage. Zuikaku landed in Kure on May 21, after a stop in Truk on May 15. The US stationed eight submarines along the expected return path of the ships to Japan, but the submarines could not attack. Japan's Naval General Staff estimated Shkaku's repair and resupplied in two to three months. So neither carrier can fly Yamamoto's forthcoming Midway operation. Instead, the two carriers rejoined the Combined Fleet on July 14 and fought against US forces. Three weeks later, the five I-class submarines assisting the MO operation were reassigned to attack Sydney Harbour to disrupt Allied supply lines. On 17 May, the US submarine Tautog torpedoed and sunk the I-28 en way to Truk.

After the combat, both sides declared victory. With 41,826 long tons (42,497 t) of ships sunk, the Japanese gained a tactical win over the Americans, who lost a light carrier, a destroyer, and several smaller warships totalling 19,000 long tons (19,000 t). Lexington constituted 25% of US carrier power in the Pacific. It was overstated how much the US had damaged Japan while understating their own.

The battle averted a seaborne attack of Port Moresby, reducing the threat to US-Australian supply lines. Although Yorktown's withdrawal from the Coral Sea conceded the field, the Japanese were compelled to abort the operation that started the Coral Sea Battle.

A Japanese invasion force was sent back without attaining its goal for the first time, boosting Allied morale following a string of Japanese defeats in the first six months of the Pacific Theatre. The experienced Japanese invasion troops could have overpowered Port Moresby's garrison. The US Navy also inflated the damage it caused, which caused the press to be wary of their Midway reports.

The battle's outcome influenced both sides' strategic strategy. The Allied offensive would have been more difficult without a hold in New Guinea. On the other hand, the battle was only a momentary setback for the Japanese, who focused on tactical outcomes. They validated the poor Japanese estimate of American fighting strength and their overconfident notion that future carrier operations against the US would be guaranteed victory.

The Coral Sea conflict cost Yamamoto Shkaku and Zuikaku their intended air confrontation with US carriers at Midway (Shh supported the Japanese invasion ground forces). The Japanese believed they sank two US Navy carriers in the Coral Sea, but Enterprise and Hornet might still help defend Midway. Combined with the land-based aircraft at Midway, the Combined Fleet no longer had a numerical advantage over the US Navy in the upcoming confrontation. Despite the damage sustained during the Coral Sea combat, Yorktown returned to Hawaii, giving the US three carriers to face Yamamoto at Midway. Yorktown sailed barely 48 hours after entering drydock at Pearl Harbor, allowing her to be ready for the next Japanese attack. Yorktown's planes sank two Japanese fleet carriers at Midway. Yorktown also took both Japanese aerial counterattacks at Midway aimed at Enterprise and Hornet.

Unlike the Americans, the Japanese did not consider including Zuikaku in operation. Moreover, no effort appears to have been taken to swiftly replace Zuikaku's aircraft so she could join the rest of the Combined Fleet at Midway. As a result, Shkaku's flight deck was severely damaged, and she needed almost three months of repairs in Japan.

H. P. Willmott, Jonathan Parshall, and Anthony Tully believe Yamamoto erred in supporting Operation MO with strategic assets. Yamamoto should not have committed his significant investments, especially fleet carriers, to a secondary operation like MO when he knew the crucial fight with the US would be at Midway. Because of Yamamoto's judgment, Japan's naval forces were defeated in detail at both Coral Sea and Midway. According to Willmott, all Japanese carriers should have participated if either operation was critical enough to send fleet carriers. Instead, Yamamoto made the success of the main Midway operation dependent on the secondary operation's success.

As a result of cryptanalysis, U.S. carriers appeared at the exact moment and location to thwart the Japanese. Moreover, US Navy carrier aircrews demonstrated sufficient skill and determination to damage Japanese carrier forces significantly. As a result, Japan lost four fleet carriers, the basis of her naval offensive forces, and so lost the strategic initiative in the Pacific War. Moreover, according to Parshall and Tully, Japan's numerical dominance in carrier forces was lost after Midway due to US industrial strength. "The Battle of the Coral Sea had supplied the first clues that the Japanese high-water mark had been achieved," say Parshall and Tully.

The Situation in the South Pacific

The conclusion of the Battle of the Coral Sea initially upset Australians and US soldiers in Australia, who feared the MO operation was a prelude to an assault of the Australian continent and Japan's temporary defeat. The Australian Advisory War Council regarded the battle's outcome as "disappointing" considering the Allies' knowledge of the Japanese aims. However, Gen. MacArthur informed Australian Prime Minister John Curtin of the battle's outcome, adding that "all the factors that have caused the tragedy in the Western Pacific since the war began" were still there.

Inability to support another marine invasion forced Japan to seize Port Moresby by land. On July 21, Japan launched a land invasion from Buna and Gona against Port Moresby. As of 15 May, the Allies had reinforced New Guinea with more troops (primarily Australian), beginning with the Australian 14th Brigade. It slowed, then stopped the Japanese advance on Port Moresby in September 1942 and repulsed a Japanese attack on an Allied base at Milne Bay. However, the Allies discovered a Japanese airstrip on Guadalcanal in July. The Japanese would use this base to threaten Australia's shipping lines. The Americans launched their initial onslaught against Tulagi and Guadalcanal to avoid this. However, because the Japanese failed to capture Port Moresby and were defeated at Midway, their strongholds at Tulagi and Guadalcanal were left vulnerable.

Moreover, it was four hours by air from Rabaul, the nearest significant Japanese base. On August 7, 1942, 11,000 US Marines landed on Guadalcanal and 3,000 on Tulagi and adjacent islands. In the Battle of Tulagi and Gavutu–Tanambogo, the US Marines captured a Japanese-built airstrip on Guadalcanal, and the Japanese were overpowered and nearly slain. During the following year, Combined-arms battles between Allied and Japanese forces neutralized Japanese defences in the South Pacific, inflicted irreparable losses on Japan's military, especially its navy, and contributed significantly to the Allies' eventual victory over Japan.

A Naval Construction Battalion (Seabees) built airfields on three Tuvalu's atolls from which USAAF B-24 Liberator bombers of the Seventh Air Force operated. It was used as a staging zone for the Battle of Tarawa and Makin, which began on 20 November 1943 as portion of Operation Galvanic.

The New Type of Naval Warfare

The combat was the first in which the ships never sighted or shot directly at each other. Instead, crewed planes served as the ships' offensive firepower. Thus, the commanders were engaged in new warfare, carrier-versus-carrier. For H. P. Willmot, commanders "had to deal with uncertain and inadequate communications in conditions where the battlefield had grown well beyond what had been expected but where speeds had increased even more, so compressing decision-making time." The Japanese were at a disadvantage because Inoue was too far away at Rabaul to adequately control his naval forces in real-time, whereas Fletcher was on-scene with his carriers. The Japanese admirals engaged were slow to exchange vital intelligence. The commander's choices influenced the battle's outcome. Two research employed mathematical models to assess various options. Assume the US carriers choose to sail separately (albeit still close together). The models predicted significantly less damage for the Americans, with one ship sunk but the other unscathed. The war outcome would have been the same. Let's say one side found its opponent early enough to strike first, leaving just the opponent's surviving to hit back. After all, having a different carrier isn't as good as striking first.

The Japanese carrier crews outperformed the US crews with the same number of aircraft. It was more synchronized than the U.S. strike on the Japanese carriers on May 8. The Japanese lost ninety carrier aircrews in the engagement, compared to thirty-five for the Americans. Because Japan had neither experienced reserves nor advanced training programs for new airmen, its highly proficient carrier aircrews were irreplaceable when the war began. The Coral Sea sparked an irreversible loss of Japan's veteran carrier aircrews by the end of October 1942. Torpedo bombers and defensive methods such as anti-aircraft artillery contributed to better following battles. Its significance to the US Navy increased as technology advanced, and the Allies discovered how to use it more effectively. Following the loss of Lexington, the US enhanced fuel containment and damage control techniques. Allied land-based air forces and the US Navy had inadequate coordination during this conflict, improving over time.

In 1942, the Japanese and US carriers battled again in Midway, the Eastern Solomons, and the Santa Cruz Islands, and in 1944, the Philippine Sea. Each of these battles was crucial in determining the path and result of the Pacific War.