'Se' (iii) was the Japanese evacuation of their forces from the island of Kolombangara in the Solomon islands group at the end of the US 'Toenails' campaign to take these islands (25 September/7 October 1943).

Kolombangara is an approximately circular and mountainous island just to the north-west of New Georgia island, from which it is separated by the Kula Gulf. The island is also separated from Arundel island to its south by the Blackett Strait and from Vella Lavella island to its north-east by the Vella Gulf. Kolombangara is about 18 miles (29 km) in diameter and Mt Veve, its central volcanic peak, reaches a height of 5,807 ft (1770 m). In 1941 there were about 500 native inhabitants.

The Japanese occupied Kolombangara and early in 1943 built an airstrip at Vila on the island’s slightly protruding south-east coast, which they garrisoned, under the command of Major General Minoru Sasaki, with 2,000 men of the 7^th Yokosuka Special Naval Landing Force and one battalion of Lieutenant General Hidemitsu Nakano’s 51^st Division on 23 February 1943. The army battalion was relieved by a single battalion of Lieutenant General Masatane Kanda’s 6^th Division in April of the same year. By a time late in 1943, the Japanese garrison had increased to an overall strength of about 12,400 men.

As the US forces advanced to the north-east along the chain of the Solomon islands group after their February 1943 victory on Guadalcanal at the end of 'Watchtower', the Japanese expected them to land on Kolombangara and advance from there to New Georgia, but the Americans attacked New Georgia first and subsequently bypassed Kolombangara by landing on Vella Lavella, which was only lightly garrisoned, in 'Dogeared'. The Japanese began to evacuate Kolombangara on 25 October 1943 in 'Se' (iii), in the process losing a number of ships.

Although there was no land fighting on Kolombangara, there were two naval battles and one naval engagement off the island before the Japanese undertook 'Se' (iii). The first of these was the small engagement sometimes known, if somewhat grandiloquently, as the 'First Battle of Kula Gulf'. This resulted from the departure of the Japanese destroyers Minegumo and Murasame from the Shortland islands group at 19.10 on 5 March on a routine run to deliver supplies to the Japanese garrisons of Kolombangara and New Georgia islands. The departure of the two Japanese warships was spotted, though they were reported as a pair of light cruisers. The Japanese ships headed through Vella Gulf and Blackett Strait, and by 23.30 had unloaded their embarked supplies and headed back toward the Shortland islands group. What the Japanese did not know, however, was that on a north-easterly course between Kolombangara and New Georgia there was a US bombardment force of Rear Admiral Aaron S. Merrill’s Task Force 68,which comprised the light cruisers Montpelier, Cleveland and Denver, together with the destroyers Conway, Waller and Cony. At about 22.35 the Japanese ships were detected by the radar of Consolidated PBY-5 surveillance flying boats. Minegumo and Murasame had just emerged from Blackett Strait and settled on a north-westerly course when at 01.01, the Murasame's look-outs spotted flashes of light: this was US fire at a range of about 10,000 yards (9145 m) off the Japanese ship�s starboard bow. The first 6-in (152-mm) salvo straddled Murasame, and within one minute she had been decisively hit, and was then struck by a torpedo launched from Waller. Murasame exploded and sank at 01.15 with with loss of all of her normal 200-man crew.

Minegumo was trapped and zigzagged to the north even as the US ships started to fire on her at 01.06; the Japanese destroyer returned fire, but the newly developed radar-controlled guns of the US cruisers possessed total superiority. Minegumo was hit repeatedly and sank at 01.30: some 174 of her normal crew of 180 men managed to swim to Kolombangara. The US ships sustained no damage, and then proceeded to their planned shore bombardment mission.

Next came the Battle of Kula Gulf in the early hours of 6 July between US and Japanese warships off the coast of Kolombangara. On 5 July Rear Admiral Walden L. Ainsworth’s Task Group 36.1, comprising the light cruisers Honolulu, St Louis and Helena, as well as the destroyers Nicholas, O’Bannon, Radford and Jenkins, had been informed that the Japanese were attempting another 'Tokyo Express' mission down 'The Slot' in the Solomon islands group, and after completing its replenishment at Tulagi the task group steamed to the north-west past New Georgia island in an effort to make an interception. Ainsworth did not have time to confer with his ships' captains, but they had trained together and were familiar with the battle plan. This called for a radar-directed gunnery duel at a range of between 8,000 and 10,000 yards (7315 and 9145 m). Ainsworth was working on the assumption that his force would have a clear radar advantage and that the Japanese torpedoes would be ineffective at this range, but both assumptions soon proved to be incorrect. By this time the Japanese had begun installing radar on their lighter warships, and Niizuki was equipped with the latest equipment, while the Japanese Type 93 'Long Lance' was a 24-in (610-mm) torpedo possessing considerably greater range than had yet been appreciated by Allied intelligence. Ainsworth also planned to retain a column formation with the light cruisers in the centre and the destroyers in the van and rear. From this it is clear that the US Navy had still not learned the lessons of the Battle of Tassafaronga.

The Japanese destroyer force comprised Mochizuki, Mikazuki and Hamakaze of the 1^st Transport Group and Amagiri, Hatsuyuki, Nagatsuki and Satsuki of the 2^nd Transport Group, and these seven ships were carrying 2,800 men and supplies for the reinforcement of Vila on Kolombangara and thence Munda of New Georgia. Cover was provided by the destroyers Niizuki, Sukukaze and Tanikaze of the Support Group under the command of Rear Admiral Teruo Akiyami.

The US forces were in the process of launching their next offensive in the Solomon islands group, having just landed troops on the island of Rendova, just to the south-west of New Georgia, as a preliminary step to seizing the major Japanese air base at Munda on New Georgia. In support of this landing, which was to designed to create an initial beach-head for the subsequent movement of US troops across Blanche Channel to New Georgia, Ainsworth had undertaken a cruiser bombardment of Vila on Kolombangara and Bairoko on New Georgia during the previous night. Then, short of fuel and ammunition, the US warships were in the process of retiring to the Coral Sea to replenish in preparation for the support of a US Marine landing scheduled for the north coast of New Georgia on 10 July.

At 01.06 on 6 July, off Kolombangara, TG36.1 came into radar contact with the Japanese reinforcement group. The Japanese were divided into the 1^st Transport Group and 2^nd Transport Group, with the Support Group trailing the main column. It was the Support Group which was the first to come under attack. The US ships opened fire at 01.57, firing 612 rounds in 21 minutes 6 seconds, quickly sinking the destroyer Niizuki and killing Akiyama. Helena had expended all of her flashless powder during the previous night’s bombardment, however, and had perforce to use smokeless powder, the resulting muzzle flashes revealing her to the Japanese ships with every salvo fired. Two of the Japanese destroyers launched their torpedoes and hit Helena, fatally damaging her. The main Japanese force, which had reversed course from Vila with the first contact, then broke away, having landed only 850 of the 2,800 troops, of whom the remaining 1,950 were killed or brought back to base. The Japanese destroyer Nagatsuki ran aground and could not be towed off, and Hatsuyuki was damaged.

Both forces began to withdraw from the area, but one Japanese and two US destroyers remained to rescue survivors. At about 05.00, the destroyers Amagiri and Nicholas exchanged torpedoes and gunfire. The Japanese destroyer was hit and retired. The beached Nagatsuki was abandoned by her crew in the morning, and the ship was then bombed by aircraft from Henderson Field on Guadalcanal. The destroyer caught fire, and later in the same day her magazines exploded.

The destroyers Radford and Nicholas both remained to search for and rescue survivors from Helena. While rescuing over 750 men, Radford and Nicholas had to re-engage the Japanese three times. While retiring, Amagiri rammed and cut in half the motor torpedo boat PT-109 in Blackett Strait, to the south-west of Kolombangara, on 2 August.

The Battle of Kula Gulf cost the US Navy one light cruiser sunk and 168 men killed, and the Imperial Japanese navy two destroyers sunk and 324 men killed, as well as two destroyers slightly damaged and another two moderately damaged by gunfire.

During the night of 12/13 July the Japanese had despatched another reinforcement, this time of about 1,200 men, by destroyer transports to New Georgia. Under the command of Rear Admiral Shunji Izaki in the light cruiser Jintsu, the Japanese force comprised the destroyers Satsuki, Minazuki, Yunagi and Matsukaze as the Transport Group, and Mikazuki, Yukikaze, Hamakaze and Kiyonami as the Support Group.

The week before, the USA had landed elements of the 37^th Division on New Georgia to attack Munda, and had just landed marine raiders at Rice Anchorage on New Georgia�s north coast to seize Bairoko. It was the task of Ainsworth’s light cruiser and destroyer force to protect the north coast beach-head from attack by the 'Tokyo Express' and if possible to prevent the landing of Japanese reinforcements from landing. The Japanese destroyer movement was detected by Allied intelligence, and Ainsworth was dispatched from Tulagi to intercept. For this operation, Ainsworth’s Task Force 18 was assigned six additional destroyers by Rear Admiral Richmond K. Turner, commander of the Amphibious Force, South Pacific, and thus comprised the light cruisers of Cruiser Division 9 (US Honolulu and St Louis and New Zealand Leander), and the destroyers of Destroyer Squadron 21 (Nicholas, O�Bannon, Taylor, Jenkins and Radford) and part of Destroyer Squadron 12 (Ralph Talbot, Buchanan, Maury, Woodworth and Gwin). The light cruisers constituted the centre of Ainsworth’s column, with groups of five destroyers ahead of and to the rear of the cruisers. The US commander�s plan was to send the van destroyers to fire torpedoes, close with the light cruisers to engage with 6-in (152-mm) gunfire before the Japanese could react, then turn away to avoid the inevitable response of Japanese torpedo salvoes.

Allied air cover prevented the Japanese from sighting Ainsworth�s force, while radar-equipped PBY-5 flying boats tracked the Japanese force’s advance to the south-east down 'The Slot'. The ships of TF18 established radar contact with the Japanese ships at 01.00 on 13 July, and the detection was confirmed visually just a few minutes later. At 01.09, in the belief that he had total tactical surprise, Ainsworth issued the order for the van destroyers to fire torpedoes. The Japanese had detected the Allied radar emissions using a new radar detection system, however, and had already spotted the Allied ships at 01.08. Jintsu turned on her searchlights and opened gun and torpedo fire. The Allied cruisers also opened fire, using FC radar fire control and spotting from the Catalina flying boats. Jintsu was quickly smothered by shell fire and put out of action, and by 01.45 had been hit by two torpedoes and sank with almost all hands, including her captain and Izaki.

It was now time for the ships of TF18 to turn away with the object of avoiding Japanese torpedoes, but communications were poor and the movement was executed poorly. Leander was hit by a torpedo whose detonation also killed 28 men, and was forced to pull out of the battle escorted by Radford and Jenkins. Other ships only just escaped the Japanese torpedoes.

The Catalina flying boats reported that four Japanese destroyers were heading to the north-west, and Ainsworth detached Destroyer Squadron 21 in pursuit. The Japanese had, in fact, taken cover in a rain squall to reload their torpedo tubes. Ainsworth soon had most of his force racing up 'The Slot', but TF18 was disorganised and there was real danger of a 'friendly fire' incident in the confusion. US radar detected two targets, but it took several minutes before it could be established that these were in all probability Japanese ships, and by this time the Japanese had fired their torpedoes and were retiring. TF18 steamed straight into the path of the �Long Lance� torpedoes: at 02.08 St Louis was hit well forward, and while she manoeuvred violently Honolulu was nonetheless hit right in her bow and also near her stern by a torpedo; fortunately, the latter weapon failed to detonate. The destroyer Gwin was hit by a torpedo in her engine room and suffered an immediate secondary explosion; the ship was scuttled at 09.30. Only Ralph Talbot was able to fix on a target, and fired torpedoes at 02.13, but all of these missed.

As the remaining warships of TF18 returned down 'The Slot', a force of 18 Aichi D3A 'Val' dive-bombers and 20 Mitsubishi A6M Reisen 'Zero' fighter-bombers tried to attack them, but were driven off by fighters from the Russell islands group.

All three Allied cruisers had been hit well forward and were relatively lightly damaged. Even so, these ships had to be taken in hand for lengthy repairs and refitting, the latter including, for the US ships, the replacement of their 1.1-in (28-mm) light anti-aircraft weapons by altogether more effective 40-mm Bofors anti-aircraft mountings. Honolulu and St Louis were out of action for several months, while Leander was under repair for a year and in fact did not return to action during World War II. Except for Jintsu, the Japanese force escaped damage. The Allies lost 89 men killed, and the Japanese 482 men killed. The Battle of Kolombangara was a Japanese tactical victory, but the cumulative effect of this and other such engagements in the water of the Solomon islands group was a Japanese operational defeat.

At considerable cost, Ainsworth had achieved his primary mission of preventing any Japanese attack on the marine raiders' beach-head and, in combination with the earlier Battle of Kula Gulf, successfully deterred the Japanese from future use of Kula Gulf as an avenue for the reinforcement of Munda. After the Battle of Kolombangara, the Japanese therefore used Vella Gulf, Blackett Strait and the more constricted passage at Wana Wana, resulting in a series of nightly attacks by US destroyers and PT boats against their reinforcement efforts.

The Japanese destroyer transports had reversed course as soon as the battle began, and had been able to land 1,200 troops on the west coast of Kolombangara before withdrawing.

In 'Se' (iii), under the command of Rear Admiral Baron Injuin Matsui, from 25 September the Japanese moved about 100 assault boats and other small craft to the north coast of Kolombangara for the evacuation of Sasaki�s garrison. Cover was provided by 11 destroyers and the submarines Ro-105, Ro-106 and Ro-109, one of which attacked but missed the US light cruiser Columbia. US destroyer forces were then deployed to blockade Kolombangara: on 27/28 September these were Charles Ausburne, Claxton, Dyson, Spence and Foote; on 29/30 September Patterson, Foote, Ralph Talbot and McCalla; on 1/2 October Waller, Eaton, Cony, Radford, Saufley and Grayson; on 2/3 October Ralph Talbot, Taylor and Perry; and on 3/4 October Radford, Saufley and Grayson once again. Even so, the Japanese under the command of Captain Baron Matsuji Ijuin, commander of Destroyer Squadron 3, were able to evacuate some 9,400 men in destroyers, fast transports, assault boats and other craft, although about one-third of the small craft and 1,000 men fell victim to the US destroyers.

After their defeats on New Georgia and in the Battle of Vella Gulf, the Japanese had evacuated their remaining garrisons in the central sector of the Solomon islands group, as part of this effort had established a staging post for evacuation barges at Horaniu on the northern tip of Vella Lavella. In October there remained for evacuation some 600 men, and on 6 October a force of three older destroyer transports (Fumizuki, Matsukaze and Yunagi escorted by six modern destroyers (Akigumo, Isokaze, Kazagumo, Yugumo, Shigure and Samidare) was sent under the command of Ijuin as the Vella Lavella Evacuation Force to recover them.

Rear Admiral Theodore S. Wilkinson, commander of the Amphibian Forces, South Pacific, received the air sighting reports during the afternoon. The only force in the immediate area was Captain Frank R. Walker’s group of three destroyers (Selfridge, Chevalier and O’Bannon). Wilkinson ordered a second group of three destroyers (Commander Harold B. Larson�s Ralph Talbot, Taylor and La Valette currently on convoy escort duty to the south) to join Walker’s three destroyers, but knew that these were unlikely to arrive before the Japanese did.

Walker knew that his three destroyers faced nine Japanese destroyers, and also that Japanese reconnaissance aircraft had sighted his small force. He pressed on to effect an interception, however, dodging into a squall at one point in an unsuccessful attempt to elude the Japanese air surveillance. At 22.31 look-outs on Walker’s ships sighted the Japanese force, and Walker steered for it at full speed, uncertain as to whether or not Ijuin would break off when challenged, as he had done in earlier engagements. On this occasion Ijuin chose to fight, though only after he had ordered his destroyer transports to withdraw. Ijuin’s force was divided into a column of four destroyers from his own Support Group and a second column of two destroyers which had been escorting the Transport Group and was now racing to join up. Ijuin sighted the US ships at 22.35, but was initially uncertain whether or not this was his own Submarine Chaser and Transport Group (four submarine chasers, four motor torpedo boats and four landing craft).

Walker ordered his destroyers to launch torpedoes at a range of 7,000 yards (6400 m), and a few moments later to open fire with their guns. The US commander continued on course, a dangerous move in the face of the likelihood of a Japanese torpedo riposte. Ijuin was poorly placed to fire his own torpedoes, however, as Yugumo had charged off to meet the Americans and thereby fouled the Japanese line of fire. Ijuin hauled the other three destroyers in his column to the south and thus evaded the US torpedoes, but Yugumo was hit by shells and one torpedo, and left adrift and burning to sink at about 23.10.

As she tried to close with the Submarine Chaser and Transport Group, Chevalier was struck by a torpedo whose detonation exploded her forward magazine. Moments later, as she veered off course, she was rammed in her after engine room by O’Bannon: the two ships remained locked together for some time. Meanwhile Selfridge charged ahead and into a spread of Japanese torpedoes, one of which impacted at 23.06 and wrecked the destroyer’s forward part.

At this point Larson�s three destroyers, arriving from the south to reinforce Walker, swept into the battle. Japanese reconnaissance aircraft had sighted the ships but reported them as cruisers, and Ijuin decided that he was now outmatched and opted to withdraw. However, his parting salvo at Walker’s crippled ships failed to find at target. Selfridge managed to get away, but Chevalier was sent to the bottom at about 03.00 by a torpedo from La Vallette.

The battle had cost the Americans one destroyer sunk and another two severely damaged, as well as 64 men killed, 47 wounded and 36 missing, and the Japanese one destroyer sunk and 138 men killed.

While the Americans were undertaking rescue and salvage operations, the Submarine Chaser and Transport Group slipped past them and embarked 589 men from Vella Lavella.

Thus ended the second phase of the 'Cartwheel' strategic operation, in which the Allies had taken the central portion of the Solomon islands group in a three-month campaign which had cost them six ships and the Japanese 16 ships.