Battle of the Coral Sea, 4-8 May 1942

Japanese intentions

By April 1942 the Japanese had formed a defensive perimeter which stretched from the Kuriles southward through the Marshall Islands to New Britain, then westwards to Java, Sumatra, the Andaman Islands and Burma. Within that perimeter Japanese authority was, or soon would be, unchallenged and every strategic position occupied. In the South-West Pacific Area outposts were held at Lae and Salamaua in northern New Guinea.

Yet the Japanese were not quite satisfied with their conquests. Impressed by the ease with which they had achieved their strategic goals, a number of Japanese leaders began to consider extending the perimeter to gain an extra measure of security. The Commander-in-Chief of the Imperial Japanese Navy, Admiral Isoroku Yamamoto, was concerned that despite the crushing blow dealt at Pearl Harbor to the US battle fleet, the strike force had missed the aircraft carriers. These ships were beginning to make their presence felt with a number of raids on Japanese bases in the central and south Pacific. These considerations were given further impetus by the Doolittle raid on Tokyo using medium bombers launched from the aircraft carrier USS Hornet from a position well within the defensive perimeter. Yamamoto wished to fight the decisive battle which would complete the destruction of the US Pacific Fleet before it was able to rebuild its strength. By doing so he hoped to gain the time needed to consolidate the Empire's defences. He began planning for a move against the island of Midway.

In the South Pacific the Japanese Army was keen to extend the perimeter to provide defence in greater depth for the base at Rabaul and also to cut the lines of communication between Australia and the west coast of the United States. Japanese operational doctrine held that advances should always be made under cover of land-based aircraft. This doctrine governed the choice of new targets and had been rigidly adhered to in operations in China and in the Pacific. Techniques had been developed to bring newly captured airfields into use as quickly as possible.

In this context the Solomon Islands could be seen as an opportunity for expansion south to New Caledonia, the New Hebrides and Fiji; they could also be seen as a highway for an Allied offensive aimed at Rabaul. Port Moresby was also in air striking range of Rabaul and the Japanese were becoming concerned with the build up of Allied air power in the area. Conversely, its occupation would lead to Japanese aerial dominance of north-eastern Australia. Nauru and the Ocean Islands would also be occupied.

Consequently the Japanese put in train Operation MO. The object of this operation was the capture of Port Moresby in New Guinea and Tulagi in the southern Solomons. The forces allocated to the operation were:

1. A group consisting of a seaplane tender supported by two light cruisers, three gunboats and minelayer would establish an air base at Deboyne island in the Louisiade Archipelago.
2. A landing group of eleven transports and a number of small supply ships, escorted by a light cruiser and six destroyers, to assault Port Moresby.
3. A covering force for the landing group consisting of the light carrier Shoho, four heavy cruisers, a destroyer and a tanker.
4. A carrier striking force consisting of the fleet carriers Shokaku and Zuikaku, two heavy cruisers and six destroyers and a tanker to operate in the Coral Sea to destroy any Allied force attempting to interfere.
5. A force of seven submarines to provide distant reconnaissance and attack any opposing forces.
6. A landing group of one troopship with a seaplane carrier a minelayer and some smaller vessels, escorted by two destroyers, to occupy Tulagi.
7. Land-based air support from aircraft of the 25th Naval Air Flotilla, based mainly at Rabaul but with detachments at Buna, Lae and the Shortlands.

During late April and early May these forces began their movement south.

The battle - 4—8 May 1942

As the Japanese made their preparations for the invasion of Port Moresby and the occupation of Tulagi, the US Navy, forewarned by signals intelligence of the impending operation, made their dispositions to counter it. On 1 May two carrier task forces, Task Force 17, built around USS Yorktown (Rear Admiral Frank Jack Fletcher), with 3 heavy cruisers and 6 destroyers (one escorting an oiler), and Task Force 11 consisting of USS Lexington (Rear Admiral Aubrey B. Fitch), 2 heavy cruisers and 7 destroyers rendezvoused off Espiritu Santo. From Sydney Task Force 44, consisting of the heavy cruiser HMAS Australia and the light cruiser HMAS Hobart, under the command of Rear Admiral J. G. Crace, RN, departed Sydney (eventually to join the carriers on 4 May). The cruiser USS Chicago and the destroyer USS Perkins, also part of Task force 44, came up from Noumea.

On 2 May the two task forces separated when Fletcher, leaving Fitch replenishing, steamed north-west to a reach a position 550 miles south of Guadalcanal by dawn on the 3rd. That day, covered by the Shoho's group, the Japanese occupied Tulagi, and established a seaplane base with six A6M2-N floatplane fighters. The Japanese carrier striking force remained north of Rabaul. Fletcher heard of the occupation of Tulagi that evening. He detached his oiler and its escorting destroyer and proceeded north at high speed.

Task Force 17 reached a position 110 miles south of Tulagi on the morning of 4 May and at 6.30 am launched a strike comprising 12 TBD torpedo bombers and 28 SBD dive bombers. The attack went in between 8.15 and 8.30, catching the Japanese by surprise. The dive bombers sank two small minesweepers and damaged the destroyer Kikuzuki beyond repair. Minor damage was inflicted on a minelayer and supplies on the beach. The torpedo bombers sank the minesweeper Tama Maru. A second strike destroyed five of the six aircraft based there, and a third sank four landing barges. Three aircraft from the second strike were lost, the others suffering no casualties. The strikes gave a valuable edge to the Yorktown's Air Group's efficiency, which had been built up over nine weeks of intensive training.

Realising that the Japanese would now be aware that there was at least one American carrier in the offing, Fletcher quickly retired southwards through the night to rejoin Task Force 11 at dawn on 5 May in a position some 400 miles south of Tulagi. This force had been joined by Task Force 44 the previous day. The Allied force spent the day replenishing.

Meanwhile, the Japanese Carrier Strike Force had moved rapidly down the eastern flank of the Solomons and by midday on the 5th they were to the east of San Christobal Island, covering what they anticipated to be the US carriers' line of retreat. Traditionally the American carrier task forces had rapidly cleared the area after a raid.

All through 6 May the opposing forces remained in ignorance of each other's whereabouts. The Japanese carriers rounded San Christobal and steamed westwards to a position 100 miles south of Guadalcanal, then turned south. They flew no searches that day, leaving reconnaissance to the long-range aircraft of the 25th Air Flotilla based mainly at Rabaul. The American carriers remained roughly in the same area all day and at one stage the fleets were only 80 miles apart.

The Japanese Port Moresby invasion force was moving south and by nightfall of the 6th was just north of the Louisiades. Its covering force, the Shoho and her accompanying cruisers, had refuelled after covering the Tulagi landing. They then moved south-westwards towards the Jomard Passage. They were sighted and unsuccessfully attacked by B-17s from Australia. When enough information became available to make the Japanese intentions apparent, Fletcher, having amalgamated his three task forces to form the single Task Force 17, steamed westwards through the night in preparation for launching search flights at dawn. The fleet tanker Neosho and her escorting destroyer Sims were left to steam southwards to a new refuelling position.

On the morning of 7 May Fletcher turned Task Force 17 to the north. At 6.45 am he detached Crace's Support Group, now redesignated Task Group 17.3, to the north-west, towards New Guinea. The group comprised the Australia and Hobart, USS Chicago and the destroyers USS Perkins, Wallke and Farragut. Crace's mission was to prevent any Japanese force debouching from the Jomard Passage into the Coral Sea. Both the Japanese and US carrier forces launched searches at dawn. At 8.15 am American scouts sighted a force (reported as 2 carriers and 4 cruisers) 225 miles to the north-west.

At 9.26 am Lexington launched 28 SBDs, 12 TBDs and ten F4F-3 fighters. Twenty minutes later the Yorktown launched 23 SBDs, 10 TBDs and 8 F4Fs. Although the search aircraft had actually discovered and mistakenly identified the force bound for Deboyne Island, en route to their target the strike aircraft sighted the Shoho and, at 11.00 am, attacked her. Hit by 13 bombs, up to 7 torpedoes and a crashed SBD she sank at 11.35 am with a loss of 638 dead. Three aircraft were lost. By that time the Port Moresby landing force, aware of Crace's blocking force and having been bombed by land based aircraft, had turned back permanently and the strategic objective of the Allies had been achieved.

Further to the east the searches launched by tile Japanese Carrier Striking Force were successful in sighting the Neosho and Sims at about 8.30 am. They were mistakenly reported as a carrier and light cruiser. After two unsuccessful level bombing attacks by B5Ns the two ships were attacked by 36 D3A dive bombers at noon. The Sims was sunk and the Neosho heavily damaged but remained afloat until discovered and sunk by friendly forces on 11 May. While these strikes were airborne Admiral Takagi, commanding the Japanese Carrier Striking Force, received his first intelligence of the position of the American carriers. To his chagrin he was unable to launch a strike until late that afternoon. The Japanese pilots missed Task Force 17 and on the return flight they were intercepted by American fighters and badly mauled. Further heavy loss resulted from their inability to find their carriers in the dark and only four aircraft landed of the 27 despatched.

That night, the two carrier groups drew away from each other, the Americans moving south to find better weather for the next day's operations, the Japanese steaming north to avoid precipitating a night battle.

Task Group 17.3 had also been in action that day. After being detached by Fletcher that morning Crace had proceeded at 25 knots to take up a blocking position south of Jomard Passage. At 2.47 pm, when the force was 70 miles south of Deboyne Island, aircraft were engaged ineffectively at long range. At 3.06 pm 12 G3M torpedo bombers attacked the force with no result despite some near misses. The ships were then strafed. Five bombers were claimed shot down. Immediately following this attack the Australia was subjected to an accurate level bombing attack which was avoided by skilful ship handling. A few minutes later three American high level bombers bombed the ships with no result. Task force 17.3 remained on patrol until 1.00 am on 10 May then proceeded to Australia, arriving at Cid Harbour on the 11th.

Returning to the carrier forces: at 6.00 am on the morning of 8 May, the Japanese, who had steamed southwards during the night, launched searches to cover a south-east to south-west arc. Fifty-one strike aircraft and 18 fighters were ranged in readiness. The American carriers launched 18 SBDs on an all round search at 6.25 am. The two carrier groups were each detected at approximately the same time. The Americans launched 24 bombers and nine torpedo bombers and six fighters from the Yorktown and 24 bombers, 12 torpedo bombers and l0 fighters from the Lexington. Yorktown's aircraft sighted the Japanese at 10.32 am. As the American aircraft approached, the two carriers separated, with Zuikaku disappearing into a squall. The Shokaku, however, turned into the wind and began to launch aircraft. Attacked by defending fighters and defended desperately by their own, the dive bombers attacked the Shokaku scoring two hits. The torpedo bombers dropped from too far out and all missed. The flight deck was damaged preventing aircraft launches, though not recoveries, for an hour; a gasoline fire started up and the aero-engine workshop was wrecked. The Lexington's group did less damage. Many were unable to find the target and only 11 TBDs, 4 SBDs and 6 F4Fs attacked. They scored only one bomb hit.

Meanwhile, the Japanese attacked the US carriers which they caught at a time when their combat air patrol had too little fuel to intercept and the relief patrol with insufficient time to scramble and intercept the attackers. The carriers were desperately defended at low level by those SBDs which were airborne on anti-submarine or reconnaissance patrols as well as two F4Fs which had been launched in time. The Yorktown was fortunate, avoiding all torpedoes and being hit by only one 250-kilogram bomb. The bomb hit started fires below decks which were quickly brought under control.

The Lexington was less fortunate. Larger and less manoeuvrable than the Yorktown, the carrier was pinned by a well coordinated attack by six aircraft, three converging from either bow. At 11.20 am she was hit twice on the port side, forward and amidships. Dive-bombing was less successful, only two light bombs hitting the ship although near misses buckled her hull plates.

This attack is believed to have cost the Japanese 20 aircraft. It was, however, to cost the Americans the Lexington. At first glance the carrier was not grievously damaged. Counter-flooding had corrected the list caused by the torpedo damage and three fires were burning which could normally have been brought under control. Unfortunately, the damage from the near misses had so distorted her hull that the lifts were stuck in the "up" position and her aviation gasoline tanks were leaking. Although the carrier continued to operate aircraft until 1.45 pm, a spark ignited the gasoline vapour and the resulting inferno forced the abandonment of the ship shortly after 5.00 pm. She was torpedoed and sunk by the destroyer Phelps at 8.00 pm. Two hundred and sixteen of her crew were lost.

Both forces were now too battered to continue the fight. The Zuikaku escorted her damaged sister back to Japan. In the course of the voyage the Shokaku came close to capsizing in a gale. Fletcher retired to the New Hebrides and then to Pearl Harbor, arriving on 27th May.

Australia's involvement

Australia was involved in the Coral Sea battle from the very first when locally-based signals intelligence units made a significant contribution to the early detection of the Japanese thrust. Combining this information with that gleaned from coastwatchers and aerial reconnaissance the Combined Operational Intelligence Centre in Melbourne issued an assessment on 25 April that a Japanese operation to occupy Port Moresby was imminent. Aerial reconnaissance flights were flown from Australia and Port Moresby by USAAF and RAAF aircraft. Eleven US submarines based in Brisbane were deployed to the Papua area.

The Japanese force tasked with the occupation of Tulagi was sighted en route to its destination by aircraft and, on 2 May, by coastwatcher D. G. Kennedy on Ysabel Island. The small Australian garrison at Tulagi was withdrawn the same day.

Meanwhile, on 1 May Task Force 44 (Admiral J. G. Crace, RN), consisting of the heavy cruiser HMAS Australia (Captain H. B. Farncomb, RAN) and the light cruiser HMAS Hobart (Captain H. Howden, RAN), departed Sydney under orders to join the US carriers. After refuelling from HMAS Kurumba in Hervey Bay the two cruisers proceeded east, joining the US force on 4 May. On that day a concentration of transports and warships was sighted at Rabaul by Australian-based aerial reconnaissance and Shoho was seen 40 miles south of Bougainville.

5 May was spent refuelling and on the 6th the entire force was amalgamated as Task Force 17. Crace, with Australia, Hobart, the heavy cruiser USS Chicago and the destroyers USS Perkins and Walke, commanded the Support Group, designated Task Group 17.3. It was late on this day that enough information had been gathered and assessed to make clear the Japanese intention to move south through the Jomard Passage.

At 7.00 am the Support Group, reinforced by the destroyer USS Farragut, was detached to the north-west to block any Japanese force debouching from the Jomard Passage. It was soon sighted by Japanese reconnaissance aircraft. Crace proceeded at 25 knots to take up a blocking position south of Jomard Passage. At 2.47 pm, when the force was 70 miles south of Deboyne Island, aircraft were engaged ineffectively at long range. At 3.06 pm 12 G3M torpedo bombers made a determined attack on the force. Dropping their torpedoes at a range of between 1,000—1,500 metres the aircraft came onto strafe the ships. The torpedoes were narrowly avoided by skilful handling of the cruisers. Five bombers were claimed shot down. Immediately following this attack the squadron was subjected to an accurate level bombing attack by nineteen aircraft. The Australia was narrowly missed, again being skilfully conned by Captain Farncomb. A few minutes later three American high-level bombers bombed the ships with no result.

Admiral Crace was uncertain about what was occurring at that stage as he had received no situation reports from Admiral Fletcher, although intercepts of Australian reconnaissance reports and from US aircraft radios gave some indication of the carrier battle in progress on the 8th. That evening, the Hobart, short of fuel was detached to Brisbane as was the Walke, which had engine defects. The remainder of Task Group 17.3 remained on patrol until 1.00 am on the 10th then proceeded to Australia, arriving at Cid Harbour on the 11th, where the ships refuelled again from the Kurumba.

Although Task Force 17.3 had not gone into action against the Port Moresby Landing Force its presence, combined with bombing attacks from shore-based aircraft, was important in influencing the decision by the Japanese Commander-in-Chief to turn back the landing force early on 7 May — thereby achieving the Allies' strategic objective for the battle.

Carrier task forces had conducted simultaneous raids on the Gilberts and Marshalls, Wake Island and Marcus Island during February and March in an attempt to divert Japanese strength from the South Pacific. In the southern area, a raid had been attempted against Rabaul in February by the Lexington, but it was cancelled when the attacking force was discovered. On 10 March the Japanese were attacked by aircraft from the Yorktown and Lexington at Lae and Salamaua, where they had landed on 8 March. The strike force was launched from a position 45 miles south of New Guinea and flew through a gap in the Owen Stanley Ranges. The most spectacular raid, and that which concerned the Japanese most, was the bombing of Tokyo by US Army B-25 bombers launched by the carrier USS Hornet from a position well within the Japanese defensive perimeter. These raids did not cause extensive damage, but they did provide valuable operational experience for the US carrier force. More importantly, they gave weight to those voices in the Japanese High Command which favoured further expansion of the defensive perimeter.