Guns Versus Torpedoes: The Battle of Kula Gulf

The Battle of Kula Gulf, fought in the early morning hours of 6 July 1943, pitted U.S. Navy Task Group 36.1, a force of three cruisers and four destroyers, against a scattered Japanese force of ten destroyers. Rear Admiral Walden Ainsworth, commanding the U.S. force, counted on the 45 6-inch guns of his cruisers to overwhelm the Japanese ships. Ainsworth correctly believed that the radars in his ships would allow him to engage the Japanese before they spotted his force.

But when the inevitable confusion of night combat loomed, he found that he was engaging the three destroyers of Rear Admiral Teruo Akiyama’s screening force later and at shorter ranges than he planned. “Night Fight at Kula Gulf” in the July issue of Naval History describes how Japanese night optics, torpedoes, and training combined to sink the cruiser USS Helena (CL-50) in the opening minutes of the action.

In return, Ainsworth’s guns annihilated the destroyer Niizuki, Akiyama’s flagship. The Niizuki’s companions, the destroyers Suzukaze and Tanikaze, took minor damage and withdrew behind a smoke screen after emptying their 16 torpedo tubes, hitting the Helena three times and the cruiser St. Louis (CL-49) with a single dud. Neither destroyer was out of the fight, as each carried eight additional torpedoes that could be loaded into their tubes in as little as ten minutes. But both dropped off Ainsworth’s radar screens in the first fifteen minutes of the action.

This battle took place at the northern mouth of Kula Gulf, a funnel-shaped body of water with a wide northern entrance and a cramped southern entrance made hazardous by reefs, rocks, and American mines. Akiyama’s force had been screening two transport units farther south in the gulf. These were the First Transport Group (the destroyers Mochizuki, Mikazuki, and Hamakaze) commanded by Captain Orita Tsuneo Orita, and the Second Transport Group (the destroyers Amagiri, Hatsuyuki, Nagatsuki, and Satsuki) commanded by Captain Katsumori Yamashiro. The First Transport Group was already deep within the gulf, but the Second Transport Group was not. Akiyama had called it northward in response to a false sighting by the Niizuki’s radar, only to order it back south shortly before glimpsing Task Group 36.1. Whether recalled by Akiyama or simply steaming to the sound of the guns, Yamashiro turned his formation north again and bent on 30 knots just as the 6-inch rifles in Ainsworth’s cruisers began to talk at 0157.

The Second Transport Group possessed advantages and disadvantages as it steamed toward battle. While its ships were not as modern as the Niizuki, Suzukaze, or Tanikaze, they still carried 30 torpedoes. And while these torpedoes were also not of the most modern type, even the oldest among them could travel faster, reach farther, and hit harder than their American counterparts.

Crowded Decks and a Looming Showdown

Yamashiro’s main disadvantage came from the troops and supplies he carried. These crowded his decks and hampered his crews. He led his formation in the Amagiri, with the Hatsuyuki, Nagatsuki, and Satsuki following in that order. He would have seen the gun flashes from Ainsworth’s cruisers as he came north, as they shot intermittently until 0215. None of this fire was directed at Yamashiro; Akiyama’s three destroyers held the attention of Ainsworth’s ships. The Honolulu (CL-48) alone reported firing 866 rounds between 0157 and 0215, claiming that two enemy ships had been left aflame, two more had exploded and burned, and a fifth had “disappeared from screen.” 

While Yamashiro headed north, Ainsworth maneuvered. He had been steaming northwestward across the northern mouth of the gulf with his three cruisers in line, with two destroyers ahead of the cruisers and two behind. Now he thought he was steaming beyond the best position for his cruiser’s guns. To correct this, he ordered his ships to reverse course to the right. Executed at 0204, this turn put the flagship Honolulu on a course of 112 degrees, with the St. Louis now ahead of her. Akiyama’s torpedoes had erased the Helena from her position between the other two cruisers just before she made the turn, but the admiral was not to know this until far later in the battle. Ainsworth followed the reversal with a 30-degree turn to starboard in an attempt to close the range to the screening Japanese destroyers. As those targets disappeared from view, the admiral at 0214 ordered a turn to bring the cruisers to a course of 82 degrees, heading east across the mouth of the gulf.

Ainsworth’s timing was perfect. At 0214, Yamashiro was just arriving within the 15,000-yard short-scale range of the Honolulu’s SG radars. Worse for Yamashiro, the two cruisers were no longer focused on Akiyama’s ships. And still worse, the Americans had already seen the Second Transport Group disappear southward before Yamashiro had turned around. There was thus little chance of Yamashiro surprising them with his course reversal.

Ainsworth had wanted to fight a gunnery battle beyond visual range, relying on his guns to snuff out any torpedo counterattack before it could begin. His plan failed against Akiyama but succeeded handsomely against Yamashiro. The only wrinkle for the Americans came in the form of a radar failure, as the St. Louis’s SG radar had died at 0204. While her fire control radars continued to work, the loss of the search radar hampered the ability of her fire control crews to locate targets and sort friend from foe. Determined to be safe rather than sorry, her captain only fired at targets that the Honolulu was engaging.

Formation Disrupted

So things stood when Yamashiro approached Ainsworth’s two-cruiser line of battle. The Honolulu opened fire shortly after 0217, targeting the Amagiri at a range of 11,000 yards. Her fire was quickly effective, pummeling the destroyer with three hits from 300 shells fired. The Amagiri quickly turned away to starboard and made smoke. The Honolulu’s next target was the Hatsuyuki, which broke formation by spinning away to port. The St. Louis added her fire at 0223. All three of the shells that hit the destroyer were duds, although they did damage two of her four boilers, destroy three of her reserve torpedoes, and ignite a fire. Six men died. The Nagatsuki and Satsuki turned inside the Amagiri and led her back down the gulf. A single 6-inch round hit the Nagatsuki before she moved beyond the American fire. None of the Japanese destroyers managed to launch torpedoes, while only the Hatsuyuki got her guns into action. She fired a few rounds from her four aft-bearing 5-inch guns as she retired, but none found their target. 

Ainsworth’s tactics had succeeded in disrupting the Japanese formation before it could maneuver into a position to fire its torpedoes, but Yamashiro’s destroyers managed to run out of range without crippling damage. The captain took his ships back down the gulf to complete their primary mission of unloading their troops and supplies, only to lose the Nagatsuki to grounding off Bambari Harbor on the gulf’s western shore. The Honolulu’s gunnery officer reported engaging three targets in four bursts of fire from 0217.5 to 0235.5. He identified the first target as a three-stack light cruiser that went dead in the water after several large explosions and then “broke up.” Explosions were seen on the second target before SG radar showed it running onto the beach. The third target escaped but was believed (again, based on SG radar observations) to have beached itself farther south.

Most of this was incorrect. Yamashiro had no light cruisers and no ships with three stacks. The Amagiri (the Honolulu’s first target) never went dead in the water. The Hatsuyuki escaped without beaching herself. The Honolulu’s final target may have been imaginary, as none of Yamashiro’s ships seem to have been with the range reported for the target at the time that the cruiser was firing. The errors in interpretation were understandable, given the stress and chaos of night battle. The Americans had not yet learned that radar and even visual observations were an uncertain guide to the outcome of such actions. But guided by the radar reports, Ainsworth believed that all of Yamashiro’s ships had been accounted for.

Only at 0331 did the admiral learn that the Helena had been sunk, when the Jenkins (DD-447) reported the cruiser’s bow floating prow up with her hull number visible. By then, the admiral had completed radar sweeps of Kula Gulf and Vella Gulf (the next gulf to the west) without spotting any Japanese ships. With his surviving cruisers low on ammunition, Ainsworth detailed the Nicholas (DD-449) and Radford (DD-446) to rescue the Helena’s survivors. He took the remainder of his force back down the Slot.

Behind the Veil of Smoke

What of the Suzukaze and Tanikaze? In accord with doctrine, they retired under a smoke screen and immediately set to reloading their torpedo tubes. This took far longer than the ideal. Mechanical failures in the power reloading gear and an error in torpedo settings frustrated the Tanikaze’s crew. These forced them to abandon efforts to reload one tube. The Suzukaze’s crew was hampered by a 6-inch shell hit that had set fire to the ammunition in an antiaircraft machine-gun mount situated above two of the forward reserve torpedoes. In the words of the destroyer’s torpedo officer, “presence of mind and calmness failed” when burning 25-mm ammunition cooked off overheard. The crew loaded five tubes quickly but struggled with the other three, finally loading the last torpedo by hand. Seventy-four minutes elapsed before they had readied eight torpedoes, and neither destroyer approached Kula Gulf again until 0400. They saw neither the Niizuki nor the Americans. The Nicholas and Radford, still rescuing Helena survivors, spotted the returning Japanese on their SG radars, but the Japanese ships withdrew northwestward without making contact after closing to 13,000 yards.

The two U.S. destroyers had a lively time trying to execute their rescue duties. In addition to the radar sighting of the Suzukaze and Tanikaze, the Radford’s radar operators reported two large ships coming out of Kula Gulf at 0412. This proved to be a false alarm, but at 0516 both destroyers got a solid radar contact on another ship emerging from the gulf. This was the Amagiri, which Captain Yamashiro had elected to take home via the northern route rather than risking the gulf’s perilous southern exit.

Yamashiro stopped to rescue Niizuki survivors but got underway again upon spotting the two American destroyers. Both sides traded torpedoes and gunfire. The Amagiri and Nicholas both launched five fish; the Radford added another four. None found a billet, but at least one 5-inch shell from the U.S. destroyers struck home to start a fire in the Amagiri. She laid a smoke screen and disappeared behind it; the American guns fell silent at 0539 after seven minutes of fire.

The Nicholas’s crew believed that they had engaged a Sendai-class light cruiser, which was sunk by torpedo, and a smaller ship. TG 36.1’s cruisers and destroyers together had scored shell hits that destroyed the Amagiri’s fire control and torpedo launching circuits and wrecked one of her radio rooms. The destroyer lost 13 men. Her crew thought they had been engaged by at least two cruisers in their latest action and claimed that they had torpedoed one of them.

Even now, the U.S. destroyers were not left undisturbed. At 0612, both ships registered another radar contact to the south. This was destroyer Mochizuki, carrying Captain Tsuneo Orita. Orita, like Yamashiro, had decided that the northern exit was the lesser of two evils. The destroyer exchanged gunfire with the Americans in a skirmish that saw both sides focused more on getting out of the area than fighting to the bitter end. Fire from the Nicholas and Radford did damage a gun and a torpedo tube mounting on the Mochizuki before the destroyer withdrew out of range. The Japanese destroyer launched a torpedo, but it missed. With this, the Battle of Kula Gulf ended.

The Japanese had substantially accomplished their reinforcement mission, landing two-thirds of the embarked troops and half of the embarked supplies, although at the cost of a new destroyer sunk and an old destroyer stranded. Three hundred men, including Admiral Akiyama, were lost with the Niizuki. They believed that they had sunk two cruisers and a destroyer, and they actually did sink Helena. And but for a dud torpedo, they could have sunk or crippled the St. Louis as well.

Radar’s Role

Despite the success of the mission and the believed favorable balance of losses, Akiyama’s officers were far from satisfied. The lack of aerial reconnaissance allowed them to be caught unaware, and American radar clearly outperformed the relatively primitive unit in the Niizuki. The Japanese officers evaluating this and other night battles recognized that U.S. Navy radars now permitted both spotting and effective gunfire beyond visible sighting range, and so made the favored Japanese tactic of ambush by torpedo much harder to execute. Japanese destroyer officers clamored for radar of their own, and for the development of tactics for radar-directed torpedo attacks.

The problems with the torpedo reloading process received minute analysis. The Suzukaze’s torpedo officer pointed to a lack of training, and the Tanikaze’s report stressed equipment failures. The naval torpedo school decried shortcomings in both training and maintenance. But underlying all of this was the difficulty of performing a complicated maneuver with three-ton torpedoes in pitch-black darkness.

Admiral Ainsworth balanced the loss of the Helena against the sinking or grounding of eight to ten Japanese ships. He evaluated the Akiyama’s screening group as containing four to six ships, all sunk or grounded. He put the strength of the Second Transport Group at three or four ships, and again believed that all were sunk or run aground.

Later analysis reduced his score to one ship sunk and three badly damaged from a four-ship screening group, plus two ships sunk and two damaged from a five-ship transport group. Ainsworth disagreed; his final word was that his forces had sunk or caused the grounding of six or seven ships. Ainsworth and his officers had leaned heavily on radar to fight their battle and, while this had led to some misleading results, it also allowed the Americans to maintain situational awareness and strike effectively beyond the limits of their vision. Unsurprisingly, the after-action reports praised radar and called for more of it.

With the fog of war cleared away, it can be seen that the second part of the battle partly vindicated Ainsworth’s tactics. Even with a single cruiser supplying most of the firepower, Ainsworth stopped the Second Transport Group short of delivering a torpedo attack. U.S. gunpower could score hits beyond visual sighting range, but it remained unclear if it could inflict enough damage quickly enough to sink or cripple its targets before they could withdraw. These tactics were risky when opposed by superior Japanese night optics and torpedoes. Getting too close to an alert Japanese formation for too long could bring a devastating torpedo riposte, even where the American lookouts saw nothing. 

In contrast to his cruisers, Ainsworth’s destroyers accomplished little. He ordered them to stay tied to his cruisers for most of the battle, and they struggled to maintain their assigned stations right from the start of the action. The demands of navigating in formation with the cruisers distracted them from contributing to the fighting. The Radford and Nicholas gave good service at the end of the engagement, seeing off the Amagiri and Mochizuki, but could engage neither decisively. This was not surprising. Just as the Second Transport Group was burdened by troops and supplies when it first engaged, the U.S. destroyers had hundreds of Helena survivors on their decks. The Nicholas and Radford rendered outstanding service in rescuing so many, but 168 of the Helena’s crew died in the ship or in the water.

Admiral Ainsworth would soon get another chance to test his tactics. But that is a story for another day.