“Although U.S. Navy commanders were initially surprised by the first large-scale kamikaze attacks, they were quick to respond and within weeks were identifying measures to defend against this new threat.”

By Walter Topp

AS U.S. forces converged on the Mariana Islands in the summer of 1944, Japan’s admirals understood what was at stake. The loss of Guam, Saipan and Tinian would leave the United States in possession of airfields within B-29 bomber range of the home islands, while providing new bases for American submarines. The Marianas had to be defended.

Since the defeats at Midway and in the Solomons in 1942 and 1943, the Japanese had concentrated on rebuilding their navy and preparing for the battle that strategists in Tokyo believed would decide the Pacific war. Now that battle was upon them in the Philippine Sea.

But when it came, the encounter was a disaster for Japan. Poorly trained pilots in increasingly obsolete aircraft were massacred by better trained American aviators flying newer, more advanced planes. In order to even get within striking distance of U.S. carriers, Japanese bombers and torpedo planes had to evade superior enemy fighters only to then face a storm of anti-aircraft fire. The air battle that was fought on June 19 to 20, 1944 was so lopsided that American pilots called it a ‘turkey shoot.’ The Japanese lost more than 500 planes; the Americans fewer than 130. Three Japanese aircraft carriers were sunk – two by U.S. submarines – but six others escaped.

While some American commanders fumed over the half-dozen enemy flattops that got away, Japanese naval leaders understood the true scale of the catastrophe: Carriers were useless without planes and skilled aviators, and the loss of hundreds of irreplaceable pilots and machines signaled the end of the Imperial Japanese Navy as an effective fighting force.

Special Attack Units

Facing certain defeat, Japan’s admirals searched frantically for a way – any way – to slow the American advance across the central Pacific. They knew their only chance now was to inflict so much damage on the enemy forces that the United States might accept some form of negotiated settlement. But it was clear that the battered Japanese navy — especially its toothless carrier force — would never be able to deliver such a blow.

But if conventional air attacks could not succeed, what about unconventional attacks? Could the unsurpassed fighting spirit of the Japanese overcome the massive material and technological advantages of the United States? One officer who thought so was a Japanese navy captain named Eiichiro Iyo.

“No longer can we hope to sink the numerically superior enemy aircraft carriers through ordinary attack methods,” wrote Iyo, who had commanded the Japanese light carrier Chiyoda at Philippine Sea. “I urge the immediate organization of special attack units to carry out crash-dive tactics and I ask to be placed in command of them.”

Iyo was not the first to recommend creation of suicide units. The concept had been discussed by senior Japanese military leaders as early as 1943 and was already familiar to many pilots. Recognizing the dire circumstances Japan was facing, some officers declined to wait for senior-level approval.

In May 1944, before the Battle of the Philippine Sea, Japanese army major Katashige Takata, commander of the Fifth Army Air Squadron at Biak Island in New Guinea, led a group of volunteer pilots on a suicide mission against U.S. invasion shipping. One of his aircraft managed to damage a subchaser.

In July, while Japanese navy leaders considered the question of adopting similar tactics, Captain Kanzo Miura, commander of a Japanese air wing at Iwo Jima, shocked his pilots by ordering them to make suicide attacks against enemy ships. No American vessels were damaged in Miura’s raid.

On Oct. 15, in the Philippines, Rear Admiral Masafumi Arima personally led a strike against U.S. ships. Against the protests of his staff, Arima removed all insignias of rank from his uniform, indicating that he did not intend to return. He did not, although U.S. Navy records do not report any successful suicide attacks that day.

So, it was no surprise when Vice Admiral Takijiro Onishi, newly installed as commander of the First Air Fleet in the Philippines, told his subordinates that the only chance the Japanese had to defend the territory was to fly manned aircraft into American carriers. In fact, Onishi proposed the establishment of specially trained suicide units to his superiors.

“In my opinion, there is only one way of assuring that our meager strength will be effective to a maximum degree,” he wrote. “That is to organize suicide attack units composed of Zero fighters armed with 250 kg bombs, with each plane to crash-dive into an enemy carrier.”

The emperor’s pilots were destined to die in battle anyway, Onishi argued, so why not make the best use of them?

“These young men with their limited training, outdated equipment and numerical inferiority, are doomed even by conventional fighting methods,” he added. “It is important to a commander as it is to his men, that death not be in vain.”

Until that point, Japanese leaders had refused to sanction such tactics. But after the losses in the battles of the Philippine Sea and the Marianas, the hopelessness of the empire’s position forced them to reconsider.

Onishi soon created the first “Special Attack Unit” to carry out formally ordered suicide missions against invasion shipping in the Philippines. Dubbed kamikaze or “divine wind,” the name was a reference to the storied 13th century typhoon that scattered a Mongol invasion fleet bearing down on Japan.

On Oct. 24, 1944, Japanese aircraft conducted the first successful kamikaze attacks of the Pacific War, sinking the American escort carrier USS St. Lo (CVE-63) and damaging six other small carriers.

A Shadow Military

It is likely that Onishi’s original intent was to employ suicide attacks only in support of the Japanese navy’s Sho-Go Plan — the all-out defense of the Philippines. But the sinking of the St. Lo at the cost of a single pilot seemed to validate the concept. From that point on, suicide attacks became ever-more important components of Japanese defense plans.

In January of 1945, Japanese navy and army leaders ordered all branches of the armed forces to conscript suicide attackers. By the middle of 1945 the Japanese had created a shadow military of special units equipped with kamikaze aircraft, rocket-powered planes, suicide boats, human torpedoes, suicide submarines and even suicide sniper squads. Plans were also underway to equip soldiers with hand-carried anti-tank weapons which they would place against the sides of U.S. tanks, destroying the tank and themselves. The Japanese army air service had even created a special unit to train pilots to ram American bombers.

Although the initial Japanese kamikaze attacks against U.S. ships in the Philippines were hurriedly mounted, later strikes became increasingly sophisticated as military planners studied the results of the early missions and refined the tactics and training. Japanese commanders recognized the enormity of the sacrifice they were asking their young pilots to make; leaders at all levels made every attempt to give kamikaze pilots the training, equipment, tactics and support they needed to succeed in their missions in order to give their deaths meaning.

As the Americans advanced across the central Pacific and through the Philippines, the creation of special attack units became Japan’s highest priority. They were believed to be the empire’s only hope for fending off the final, unthinkable catastrophe.

“The Most Difficult Problem”

While some U.S. planners had anticipated the use of suicide tactics, the navy was initially shocked by the attacks. Sailors were unnerved by the realization that enemy pilots were intentionally killing themselves in hopes of destroying Americans.

Worse, kamikaze attacks were significantly more effective than conventional raids. The layered anti-aircraft defenses that had proved virtually impenetrable at the Battle of the Philippine Sea could not protect the enormous formations of warships and transports forced to operate for extended periods within range of Japanese land-based aircraft.

From October 1944 through February 1945, the kamikaze sank 28 U.S. ships, including two escort carriers and four destroyers, and damaged 140 more, including fleet carriers, battleships, and cruisers. Overall, the attacks killed more than 3,000 U.S. sailors at a cost to the Japanese of approximately 500 planes and pilots. For the Japanese, suicide strikes were an effective and sustainable tactic.

The Kamikaze had two main advantages over conventional attackers. First, the pilots were undeterred by the concentration of fighter cover or anti-aircraft fire. Unless destroyed, they were committed to the attack. Second, even if heavily damaged, or even if the pilot were killed during his final dive, the plane might still hit the target. U.S. after action reports bulge with accounts of kamikaze planes being shredded by anti-aircraft fire, their engines aflame, wings shot off, pilots dead, yet still striking American ships.

It’s little wonder that a 1945 report from the headquarters of the U.S. fleet called kamikazes, “by far the most difficult anti-aircraft problem yet faced by the fleet.”

Rapid Response

Although U.S. Navy commanders were initially surprised by the first large-scale kamikaze attacks, they were quick to respond and within weeks were identifying measures to defend against this new threat.

As soon as kamikaze tactics were identified – and the attack profiles were instantly recognizable to the astonished crews of targeted ships – the navy began devising countermeasures. By the end of 1944 there was a booklet for sailors containing the latest information on kamikaze tactics and recommended defensive measures. By the time of the Okinawa invasion in April 1945, the navy, through the new Anti-aircraft Operations Research Group – established in October 1944 – and the Special Defense Section of the Pacific Fleet staff, had developed doctrine, tactics and procedures that blunted the effect of the kamikaze onslaught. The rapid response was no accident.

Throughout the Pacific War, the U.S. Navy had demonstrated a remarkable ability to learn, innovate and evolve. In contrast, the Japanese Imperial Navy never moved on from its pre-war devotion to ‘decisive battle’ thinking. It failed to adjust its submarine doctrine to prioritize attacks against the U.S. Navy’s vulnerable supply lines. And it never modified its aviator training programs to produce the skilled pilots that were desperately needed. Even Japan’s adoption of suicide tactics came only when there were no other options, and the change came too late to affect the outcome of the war.

By mid-1944 the U.S. Navy had greatly improved shipboard damage control, introduced variable timed (VT) fuses for five-inch anti-aircraft shells; increased the anti-aircraft armament of ships, created a vast logistics infrastructure to support mobile fleet operations, developed new task force formations optimized for anti-air warfare and created combat information centers (CICs) to coordinate sensor and weapons information aboard ships.

These and other wartime innovations were possible because the interwar navy had used reforms at the Naval War College; annual fleet problems, and the decentralization of the doctrine development process to transform itself from a traditional institution to a modern, professional organization that valued officer education, experimentation, collaborative learning, information sharing, individual initiative and adaptability, as well as one that actively sought insights from all levels of the service.

“The result,” wrote author Trent Hone in his 2018 book, Learning War: The Evolution of Fighting Doctrine in the U.S. Navy, 1898–1945 “was a critical mass of naval officers prepared to make decisions in rapidly changing circumstances.”

Japanese Innovation

Although the Japanese failed to rethink their overall strategy, they were quick to apply lessons learned in combat to refine their tactics and improve kamikaze performance.

As early as November of 1944, the Japanese developed an intensive seven-day training course to turn novice flyers into effective kamikaze pilots. Topics included basic flight, evasive maneuvers and how to coordinate with multiple planes to overwhelm enemy defenses.

As the war continued, kamikaze attacks became more difficult to defeat as suicide pilot training was updated and more planes were made available. The Japanese also developed tactics that reduced their chances of being detected by American radar, including flying in smaller formations to reduce radar signatures, closely following returning U.S. aircraft and frequently changing altitude and course.

A Desperate Race

Japan’s strategy seemed to be working. Kamikaze attacks threatened to undo two-and-a-half years of U.S. Navy progress in developing effective anti-aircraft methods. The robust defenses that worked so well at the Philippine Sea struggled to cope fully with the new and evolving threat. In fact, the final year of the Pacific War would revolve around the U.S. Navy’s desperate race to defeat the kamikaze.

In a detailed analysis of anti-suicide efforts published in August, 1945, the Pacific Fleet reported that from February through May 1945 – which included the bulk of the Okinawa campaign – suicide attacks were ten times more effective than conventional attacks. To score a hit on a U.S. ship, an average of 3.6 suicide attacks were conducted, compared to 37 conventional bombing or torpedo attacks. In addition, 27 percent of kamikaze attackers managed to hit their targets, while only 2.7 percent of conventional attackers scored hits. Of course, suicide attackers suffered 100 percent attrition, as opposed to the loss of 17 percent of non-suicide planes.

But during that period, American defenses steadily improved, as the navy made more efficient use of current equipment, devised more effective tactics, and accelerated the development and deployment of new equipment.

During the Okinawa campaign, American fleets employed a highly organized multi-layered defensive scheme against kamikaze attacks that included air attacks against enemy airfields; aerial surveillance of Japanese bases; the use of radar picket ships and ground-based radar; enhanced combat air patrols; improvements in gunnery; more effective formations; use of speed and maneuver; deception; and installation of new equipment.

Attacking the Source

American officers quickly recognized that no matter how tight the air and surface defenses were, some suicide planes were bound to leak through.
To limit the number of attackers overall, U.S. Navy commanders ordered repeated strikes against kamikaze bases in the Philippines, Taiwan, Iwo Jima and Japan, as well as sorties against aircraft manufacturing plants.

Since kamikaze pilots were not skilled enough to fly from carriers, virtually all suicide missions were launched from land bases. It was hoped that hitting the sources of the raids would reduce the size and frequency of kamikaze attacks. The navy also pressed the U.S. Army Air Force to send bombers to strike enemy bases and aircraft manufacturing targets. Though initially reluctant, the air force agreed.

While these raids destroyed more than 1,000 Japanese aircraft, they did not appreciably reduce Japan’s ability to mount kamikaze attacks during the Okinawa invasion. Attacks tapered off near the end of the campaign there only because Tokyo wanted to save aircraft and pilots for the defense of the home islands. By August 1945, Japan had stockpiled more than 6,000 aircraft of virtually every description to employ as kamikazes against the anticipated U.S. invasion.

Early Warning

During the Philippines campaign, kamikazes often surprised American ships by approaching at low altitude from a nearby land mass or using cloud cover to hide their approach. Some succeeded in striking their targets before even being detected.

In planning for the invasion of Okinawa, U.S. commanders anticipated large-scale kamikaze attacks. A ring of 15 radar pickets was set up 40 to 60 miles from the invasion fleet’s operating area to give warships advance warning of Japanese air attacks from Kyushu and Taiwan. Since most American vessels by then were equipped with air search radar that could detect planes from 75 to 100 miles away, the use of radar pickets extended the fleet’s radar coverage out to 150 miles.

Initially, each picket was manned by a radar-equipped destroyer with a fighter direction team. But after several weeks of concentrated kamikaze attacks against the exposed ships, the navy began to assign landing craft, patrol boats and sometimes a second destroyer or destroyer escort to the stations to provide additional anti-aircraft capability. Eventually each picket was further protected by a combat air patrol (CAP) of up to 12 fighters, reassigned from protecting the fleet carriers.

Despite this, the radar picket ships – operating far from the robust defenses of the fleet – suffered greatly. Of the 206 U.S. ships that served in these roles, 60 were damaged or sunk by kamikazes.

As soon as possible, radar stations were established on islands around Okinawa, which allowed some of the floating stations to be abandoned. But the pickets at longer ranges from Okinawa remained in operation through the end of the campaign.

Though picket losses were high, the strategy was effective, as the radar screen extended U.S. defenses and greatly reduced the number of surprise attacks. Using picket reports, fighters could be vectored to intercept incoming raids. In fact, navy planners found the pickets so useful that they developed plans for increased use of ships in that role during the anticipated invasion of Japan. New destroyers were modified for the role by removing torpedo tubes and installing large height-finding radars, along with additional anti-aircraft guns. The navy even equipped some submarines for use in the radar picket role, though boats that were equipped with advanced radars never actually performed the function.

Despite their usefulness, pickets didn’t end the kamikaze threat. Radar technology was still crude in 1945. It was prone to malfunction and operator error. The Japanese use of aluminum strips further reduced its effectiveness. As a result, many suicide attackers slipped through the defenses.

Combat Air Patrol

In addition to detecting incoming raids, radar picket ships directed fighters to intercept positions. The navy hoped to catch the raids as far from the fleet as possible to give American pilots sufficient time to break up attacks, while staying out of the range of flak.

The combination of early warning, fighter direction, air discipline, and robust CAPs enabled U.S. fighters to drive off or shoot down nearly half of all kamikaze attacks before they reached the invasion fleet at Okinawa, including more than 60 per cent of planes approaching the American fast carrier task force.

The Navy’s Grumman F6F Hellcats and Vought F4U Corsairs were technologically superior to enemy planes – including the Mitsubishi A6M Zero fighter that had been so successful at the beginning of the war. Japanese aircraft not only lacked sufficient armor, self-sealing fuel tanks and adequate armament, but U.S. pilots were much better dogfighters. By 1945, nearly all of the emperor’s most experienced pilots had been killed and replaced by novices.

As Japanese commanders were aware that air-to-air combat would decimate their attacks, kamikaze pilots and their escorting fighters were instructed to avoid U.S. aircraft whenever possible. When intercepted by American fighters, the raiders would scatter, diving to the wavetops or scrambling for nearby clouds. A handful of escorting fighters would engage the American planes to prevent them from pursuing the suicide pilots.

If the interceptors could engage a kamikaze raid more than 50 miles from the fleet, it often broke up the attack. If the intercept occurred closer than 25 miles out, most of the scattered Japanese planes could still reach U.S. ships.

Long-range interception was so decisive, American commanders continually changed the composition of carrier air groups to include more fighters and fewer bombers, even knowing that it reduced the striking power of the fleet.

Gunnery

Japanese aircraft that escaped interception and managed to find American ships faced a gauntlet of flak.

Throughout the war, the U.S. Navy had continually improved anti-aircraft doctrine, armament and accuracy on surface ships. By 1945, fleet carriers averaged 136 separate guns of various calibers, while heavy cruisers averaged 83 guns and destroyers 42.

Defenses had to be effective at long range for times when Japanese planes were detected early, and also at very short ranges, during the final moments of the kamikaze attack. Radar-controlled five-inch/38 caliber dual purpose guns firing VT “variable time” shells incorporating tiny radar proximity fuses could attack targets at long ranges; 40-mm Bofors and gyroscopically-stabilized 20-mm anti-aircraft guns, along with machine guns, were used on close-range threats.

While gunners constantly trained to improve accuracy, the navy looked for ways to speed up anti-aircraft fire response and better coordinate and control batteries on individual ships and in formations. The combat information center (CIC) – first developed in 1942, but continually refined and improved – was critical in providing officers with a clear tactical picture of the confusing and fast-changing air battle. CICs received, coordinated, analyzed and displayed threat information from radars, radio reports, lookouts and any other source.

Despite early warning systems and robust CAPs around Okinawa, Japanese kamikazes still managed to appear without warning in the skies above U.S. ships. When that happened, a ship’s survival might depend on how fast its gunners could fill the air with projectiles. Crews responded by opening fire immediately without even waiting for perfect firing solutions. Officers would release 40-mm and 20-mm guns to sector control and ships would send up clouds of fire for as long as possible.

Formations

Since the carrier-on-carrier battles of 1942, the U.S. Navy had abandoned single carrier formations and instead formed task forces around multiple carriers.

The great battles of the Philippine Sea and Leyte Gulf demonstrated the value of two or more carriers operating together protected by one or more screens of escorting ships.

By late 1944, U.S. anti-aircraft doctrine stipulated that screening vessels should be stationed between 1,500 and 2,000 yards away from ships being shielded and from other escorting ships. This distance allowed for massed anti-aircraft fire while giving individual vessels room to maneuver if attacked.

But as Japanese mass kamikaze attacks increasingly threatened task force ships, American commanders tightened their formations and looked for other ways to strengthen defenses.

At Okinawa, U.S. Navy planners recognized that the best defense against kamikazes was the closest possible formation with a single circle of escorting vessels spaced 1,000 yards apart. Some recommended even-tighter screens, with escort vessels closing to within 200 yards of screened ships when attacks were imminent. But tighter screens increased the chance of hitting friendly ships when firing at low-level attackers, so commanders stressed the need for anti-aircraft fire coordination plans, fire discipline and rigorous training for gun crews.

To maximize the effectiveness of formation anti-aircraft defense, task force CICs delegated specific defensive tasks, like fighter direction or air search, to individual ships or groups of ships while serving as the primary nerve-center for the entire formation.

Speed and Maneuver

High speed evasive maneuvers were universally employed by ships targeted by kamikazes. While piloting a plane to the moment of impact against a maneuvering ship was easier than striking a vessel with a bomb or torpedo, colliding with a target was no easy task. Suicide pilots were mostly novice flyers. Their attack profiles, which culminated in high-speed dives, were difficult to master.

U.S. ships were instructed to go to full speed as soon as attackers appeared, making repeated tight turns and opening anti-aircraft fire at maximum range. When kamikaze planes began their final attack runs, destroyers and other small ships were directed to maneuver to bring their gunnery directors and the maximum number of guns to bear. This generally meant that ships would turn to present their beam to high-diving attackers, which had the added benefit of increasing the chance that a diving kamikaze would miss the ship. Vessels facing low-level attacks were instructed to turn away from threats to present as narrow a target as possible and protect the ship’s control station on the bridge.

There were two problems with high-speed maneuvering, particularly on smaller ships. Jinking sometimes caused fire control radars to lose a target. It also disrupted the aim of shipboard gunners. But when facing an enemy intent on diving his bomb-laden aircraft into their ships, few captains could refrain from ordering up the most radical evasive maneuvers possible.

Deception

As the toll from kamikaze attacks grew, U.S. Navy commanders looked for additional measures to reduce the threat. That’s how the high-speed transport USS Barry (APD-29) finished its days as a kamikaze decoy.

A World War I-era destroyer converted to a transport, Barry was hit by a kamikaze and heavily damaged in May of 1945. Repaired with wooden patch on her hull; all useful equipment removed; and lights and smoke pots rigged to simulate anti-aircraft fire, funnel smoke, and battle damage, Barry was towed by a fleet tug to a position where it was hoped she would attract kamikaze planes, distracting them from more worthwhile targets.
Unfortunately, the ruse worked better than anticipated. The unmanned Barry and an escorting LSM were both struck by kamikazes almost immediately. Two sailors on the LSM were killed and both ships sank.

More conventionally, U.S. amphibious ships and transports concealed themselves with smokescreens, while escorting vessels hid themselves in cloud shadows, rain squalls, and against the dark side of land masses.

Task Force 69

In July of 1945, still reeling from the mass kamikaze strikes during the Okinawa campaign and expecting even larger and more sustained attacks during the planned invasion of Japan, U.S. Navy leaders established a special task force to develop more effective countermeasures against suicide attacks.

Led by Vice-Admiral Willis A. ‘Ching’ Lee, Task Force 69 was directed to test tactics, equipment, ammunition and other elements of anti-kamikaze defense with an emphasis on improving early detection and tracking, increasing the effectiveness of anti-aircraft fire, and evaluating new weapons and procedures. The task force was allotted a former battleship – converted to a trials ship – two cruisers, two destroyers, two destroyer escorts, four auxiliary ships and two squadrons of aircraft.

The task force issued no report before the end of the war in August of 1945, but was renamed the Operational Development Force in September 1945 and continued its work. The organization later evolved into the Navy’s Test and Operational Development Force (OPTEVFOR).

A Higher State of Preparedness

Kamikaze attacks during the final ten months of the Pacific War sank 66 allied ships, damaged more than 250 others, and killed more than 6,000 U.S. sailors.

Yet, the U.S. Navy’s commitment to collaborative learning, experimentation, sharing information, individual initiative and adaptability coupled with the unsurpassed courage and dedication of tens of thousands of sailors enabled the service to blunt the impact of suicide attacks.

In a postwar history of the Navy, Captain Edward L, Beach wrote that “ships in the attack zone kept themselves in a higher state of preparedness against air threat than any warships had ever done the world over.”

Walter Topp is a former U.S. Navy officer, emergency manager, police officer, and newspaper reporter. He is currently a writer and is working on several history and emergency management projects. He speaks regularly on emergency management topics but prefers writing about military history.

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