Carriers over Rabaul

On 11 November 1943, for the second time in a week, American carrier aircraft appeared over Rabaul, the main Japanese base in the South Pacific. This time they struck from two task groups at once: from Saratoga and Princeton, which had already attacked on 5 November, and from three new ships that had only just entered combat. The Japanese counter-attack on the carriers ended in disaster, and the next day the commander of the Combined Fleet, Admiral Mineichi Koga, recalled what was left of his air groups to Truk.

War chronologies record under this date that “American aircraft continue to strike Rabaul”. That is true, but the shorthand misses what was new in those days. Since 12 October the base had been bombed mainly by General George Kenney’s land-based aircraft. The raids of 5 and 11 November were the work of US Navy carrier aviation, sent against one of Japan’s most heavily defended bases – and it was these, not yet more bomber raids, that drove the Japanese fleet out of Rabaul.

Crisis at Bougainville

On 1 November US Marines landed in Empress Augusta Bay on the west coast of Bougainville. The beachhead at Torokina was still weak, and its supply depended on transports that had to come across the open sea. The Japanese immediately tried to cut it off. On the night of 1–2 November, however, Rear Admiral Sentarō Ōmori’s force was driven back by Rear Admiral Aaron Merrill’s cruisers at the Battle of Empress Augusta Bay.

Koga did not give up. Earlier, as part of Operation RO, he had already transferred from Truk to Rabaul the air groups of the carriers Zuikaku, Shōkaku and Zuihō – 173 aircraft with the best pilots the navy still had. Now he also sent south Vice Admiral Takeo Kurita’s Second Fleet: a force of heavy cruisers escorted by a light cruiser and destroyers. Kurita was to refuel at Rabaul, put to sea on the afternoon of 5 November and smash the ships covering the beachhead by night. American reconnaissance aircraft spotted his force as early as 4 November and shadowed it all the way into harbour.

Admiral William Halsey, commanding Allied forces in the South Pacific, had no ships to hand that could stand up to such a force. Merrill’s cruisers were tired after their night action and were no match for Kurita’s heavy cruisers. In his memoirs Halsey called this situation the most serious threat he faced as commander in the South Pacific. He had one remedy left: Rear Admiral Frederick Sherman’s carrier group – Saratoga and the light carrier Princeton – which was covering the landing from a distance. Sending it against Rabaul, protected by five airfields, hundreds of anti-aircraft guns and radar, meant risking the loss of both ships. Halsey reckoned that the air groups would be cut to pieces. He gave the order nonetheless.

The strike of 5 November

On the night of 4–5 November Sherman’s carriers steamed north under cover of a weather front. At dawn they launched all 97 serviceable aircraft: Hellcat fighters, Dauntless dive-bombers and Avenger torpedo bombers. Not a single fighter was kept back on deck to defend the ships; that task was taken over by land-based aircraft from the Solomon Islands, which met the force at sea. The airmen were ordered to damage as many ships as possible rather than try to sink a few – a crippled cruiser was no longer a threat to the beachhead.

The strike arrived at around 9 a.m., when Kurita’s ships were still refuelling in Simpson Harbour. According to Japanese sources, 71 Zero fighters took off against it, 47 of them from the carrier air groups, but they could not stop the bombers. An hour later 27 of Kenney’s Liberators escorted by Lightnings came over the harbour; their bombs fell mainly on the town and the wharves.

The result exceeded expectations. The bombs damaged six cruisers, four of them seriously. Maya took a bomb above her engine room; 70 of her crew were killed, and the ship had to return to Japan for lengthy repairs. On Atago near misses killed 22 men, including her captain, and Takao and Mogami received direct hits. Chikuma, the light cruiser Agano and several destroyers were less seriously damaged. The Americans lost 10 aircraft; the Japanese – according to their own records – lost 5 fighters and one dive-bomber, although American reports claimed several dozen shot down.

What mattered most was what happened next. Kurita did not sail against the beachhead. On 5 and 6 November his damaged cruisers began to leave for Truk, which they reached by 8 November. The Japanese surface fleet virtually vanished from the Rabaul area. The threat to Torokina, which a few days earlier had seemed mortal, had passed thanks to a single morning strike, and Saratoga and Princeton returned unscathed.

The second strike

Meanwhile reinforcements arrived from the Central Pacific. At Halsey’s request Admiral Chester Nimitz lent him for a few days Rear Admiral Alfred Montgomery’s group from the newly forming Fifth Fleet: the carriers Essex and Bunker Hill and the light carrier Independence. These were ships of the first wave of the great naval construction programme, which had only just been commissioned. The group arrived on 7 November; it had to return quickly, however, since in less than two weeks it was to cover the landings in the Gilbert Islands.

Halsey decided to use both groups at once. On the morning of 11 November Sherman launched his aircraft from the area of the Green Islands, north-west of Bougainville, and Montgomery from the Solomon Sea, some 160 nautical miles south-east of Rabaul. Sherman’s group was hampered by the weather: its aircraft had to fight their way through fog and squalls, and sources differ as to whether they managed to attack effectively at all. The weight of the strike fell on Montgomery’s aircraft – about 185 of them, according to Japanese sources. Aboard Bunker Hill the new Helldiver dive-bombers made their combat debut. After the carrier aircraft came Kenney’s Liberators and land-based aircraft from the Solomons.

This time there were no heavy cruisers left in Simpson Harbour. Light cruisers and destroyers remained, and the defence was more alert than a week earlier. Even so, the attackers had their successes. The destroyer Suzunami, hit while loading torpedoes, blew up and sank with 148 of her crew. The destroyer Naganami was disabled. The light cruiser Agano lost her stern to an aerial torpedo; after makeshift repairs she left for Truk the next day, but on the way she was torpedoed by the submarine USS Scamp and reached her destination only under tow.

The failure of the Japanese counter-attack

The Japanese detected Montgomery’s group before dawn and decided to attack it in daylight. The operation went wrong from the start. There was no direct telephone link between the Rabaul airfields, word of a change in take-off time did not reach every unit, and some fighters took off too early. A group of land-based aircraft led by an inexperienced officer failed to join the formation and turned back. In the end some 70 aircraft from the carrier air groups – Zero fighters, Aichi D3A dive-bombers and Nakajima B5N torpedo bombers – flew against the carriers, together with a few land-based bombers.

The Americans were ready for them. Radar picked up the incoming formation more than 100 nautical miles from the ships. Fighters intercepted it several dozen miles short of the group; waiting above the ships were also land-based Corsairs and Hellcats from New Georgia, which were covering the carriers that day. The Japanese aircraft that got through the fighters ran into the ships’ anti-aircraft fire. No carrier was hit. The Japanese lost about 35 aircraft: every torpedo bomber that reached the target, 17 Aichi dive-bombers and several other machines. The Americans lost 11 aircraft that day.

Imperial General Headquarters in Tokyo meanwhile announced a great victory: a cruiser sunk and two large carriers, a battleship and five cruisers or destroyers damaged. None of these hits was real – like Kenney before them, the Japanese had believed their airmen’s reports.

The end of Operation RO

By the evening of 11 November the air groups of Zuikaku, Shōkaku and Zuihō were down to 52 aircraft – 39 fighters, 7 dive-bombers and 6 torpedo bombers. According to Japanese calculations, in the ten days of Operation RO these groups had lost some 70 per cent of their aircraft and almost half their aircrew. Four of the seven squadron commanders and six of the eleven section leaders were killed – men the navy had no means of replacing. The air groups of Zuikaku and Shōkaku – carriers that had taken part in the attack on Pearl Harbor and the Battle of the Coral Sea – were the navy’s last large reservoir of trained aviators.

On 12 November Koga ended Operation RO, and the next day the remnants of the air groups flew off to Truk. Land-based aircraft continued to attack the Bougainville beachhead – further “air battles off Bougainville”, as Tokyo called them, went on until early December – but without the fleet’s pilots they could no longer tip the balance. Japanese historians stress that the outcome of 11 November was decided not only by American numerical superiority but also by a new organisation of the defence: radar, fighter-direction centres aboard the carriers, destroyers vectoring fighters onto their targets, and anti-aircraft shells with proximity fuzes.

For Halsey both operations were a surprising success. The carriers had attacked one of the enemy’s strongest bases and come back without losing a ship, and the Japanese had lost the ability to use their fleet against the Bougainville campaign. The beachhead at Torokina could be built up undisturbed.

Its place in the war

The effects of the November raids reached far beyond the Solomon Islands. On 20 November the Americans landed in the Gilbert Islands, on Makin and Tarawa. For months the Japanese Combined Fleet had been preparing a plan for a decisive battle in the event of just such an attack, but its carriers were lying at Truk without their air groups, and some of Kurita’s heavy cruisers were under repair. The garrisons of the Gilberts fought alone. Japanese historians point out that using carrier aircraft to defend Rabaul was a decision taken under the pressure of the moment, and that it deprived the fleet of its main striking force precisely when it was most needed. The fleet spent six months rebuilding its air groups; the young pilots who replaced the fallen veterans suffered a crushing defeat in June 1944 at the Battle of the Philippine Sea.

Rabaul lost its importance as a fleet base. From then on Japanese warships called there only occasionally, and supplies for the garrisons on Bougainville were shipped ever more rarely until they were halted at the end of November. From 17 December, when airfields began operating in the Torokina beachhead, Rabaul was the target of daily raids by aircraft from the Solomons. In February 1944, after the American strike on Truk (Operation Hailstone), the Japanese withdrew their last combat aircraft from Rabaul. Koga did not live to see the end of this campaign: he was killed in an air crash in March 1944 – less than a year after Yamamoto’s death. Bypassed and cut off, Rabaul did not surrender until September 1945.

The strikes of 5 and 11 November showed something more as well. A year earlier, during the fighting for Guadalcanal, the US Navy had had one or two serviceable carriers in the South Pacific and could not risk them against a heavily defended base. Now new ships of the Essex and Independence classes were being commissioned one after another, and with them came new aircraft, new methods of fighter direction and new anti-aircraft defences. For the first time American carriers had attacked such a heavily defended base, full of aircraft, and come away without losing a ship. In the following months the same groups, combined into fast carrier task forces, led the offensive across the Central Pacific.