Imperial Japanese Navy in World War II

During World War II, at the beginning of the Pacific War in December 1941, the Imperial Japanese Navy (IJN) was the third most powerful navy in the world,^[3] and the naval air service was one of the most potent air forces in the world. During the first six months of the war, the IJN enjoyed spectacular success inflicting heavy defeats on Allied forces, being undefeated in every battle.^[4] The attack on Pearl Harbor crippled the battleships of the US Pacific Fleet,^[5] while Allied navies were devastated during Japan's conquest of Southeast Asia.^[6] Japanese Navy aircraft operating from land bases were also responsible for the sinkings of HMS Prince of Wales and HMS Repulse which was the first time that capital ships were sunk by aerial attack while underway.^[7] In April 1942, the Indian Ocean raid drove the Royal Navy from South East Asia.^[8] After these successes, the Japanese now concentrated on the elimination and neutralization of strategic points from where the Allies could launch counteroffensives against Japan's conquests.^[6] However, at Coral Sea the Japanese were forced to abandon their attempts to isolate Australia^[6] while the defeat at Midway saw them forced on the defensive. The campaign in the Solomon Islands, in which the Japanese lost the war of attrition, was the most decisive; they had failed to commit enough forces in sufficient time.^[9]

During 1943 the Allies were able to reorganize their forces and American industrial strength began to turn the tide of the war.

The naval war that Japan fought in the Pacific during 1941-45 reflected a very different strategy to the one the IJN had been planning and training for throughout the interwar period.^[17] This was due to the views and actions of Admiral Isoroku Yamamoto, who had assumed command of the Combined Fleet in August 1939. Yamamoto, virtually overnight, changed the passive wartime strategy of seizing the Philippines and waiting for an American naval advance to the western Pacific to a much more aggressive forward strategy.^[17] Yamamoto had first discussed an attack on Pearl Harbor in March or April 1940. After the completion of the Combined Fleet's annual maneuvers in the fall of 1940, Yamamoto had directed that a study of an attack on Pearl Harbor be performed under the utmost secrecy. By December of that year, Yamamoto had decided to conduct the Pearl Harbor operation. Yamamoto was convinced that war with the United States was inevitable, once the Japanese began any hostilities. He also believed that since a traditional victory against the United States was not possible, he had to shatter American morale and force a negotiated peace.^[17] For this reason he scrapped the passive strategy of creating a decisive battle in the western Pacific in favor of an initial blow so crippling that it would undermine American will to fight.^[17]

The operation was risky as it exposed the IJN's most powerful striking force to early destruction. Consequently, Yamamoto had great difficulty getting his plan to attack Pearl Harbor approved by a skeptical

The Japanese strategy for the coming conflict would be to fight a limited war, in which Japan would seize key objectives and then create a defensive perimeter to defeat Allied counterattacks. This would in turn lead to a negotiated peace settlement.[19] The initial period of the war was divided into two operational phases. The First Operational Phase was further divided into three separate parts; during these, the major objectives of the Philippines, British Malaya, Borneo, Burma, Rabaul, and the Dutch East Indies would be occupied. The Second Operational Phase would entail further expansion into the South Pacific by seizing eastern New Guinea, New Britain, the Fiji Islands, Samoa, and strategic points in the Australian area. In the Central Pacific, Midway would be taken as well as the Aleutian Islands in the Northern Pacific. Seizure of these key areas would provide a defensive perimeter and depth to deny the Allies staging areas from which to mount a counteroffensive.^[19]

Naval operations (1941–1942)

Pearl Harbor

On December 7, 1941, two waves of 350 aircraft from the six carriers of the Kido Butai gained complete surprise and successfully hit their intended targets.^[18] The initial attacks against Hawaiian airfields were also very successful and negated any possibility of an effective airborne defense, or the initiation of a retaliatory strike on the Japanese carriers by American aircraft.^[18] Forty B5N torpedo bombers were the most crucial part of the operation since they were to be targeted against the main battleships and carriers. Of the eight American battleships present in the harbor, five were subjected to torpedo attack and Japanese torpedo aircraft were responsible for the sinking of the battleships Oklahoma, West Virginia and California.^[18] A single torpedo hit also struck the Nevada. Additionally, torpedoes sank a target ship and a minelayer, and damaged the two light cruisers, Helena and Raleigh. In return, the Japanese only lost five torpedo bombers.^[20]

The efforts of the torpedo bombers were complemented by an additional 49 B5N configured as level bombers and armed with 1,760lb armor-piercing bombs. They dropped their payload from 10,000 feet (3,000 m), scoring ten hits. One of these penetrated the forward magazine of battleship Arizona and completely destroyed the ship.^[21] Other hits slightly damaged the battleships Maryland, West Virginia, and Tennessee. The 167 aircraft of the second wave, however, accomplished much less. This attack wave included 78 dive-bombers with the IJN's best crews.^[20] However, against stationary targets, they scored only some 15 hits including five on the Nevada, which slowly moved down the channel to the harbor entrance. Nevada was subsequently beached to avoid blocking the channel.^[20] A single bomb hit struck the battleship Pennsylvania, which was in dry dock, but caused only light damage. The light cruiser Honolulu also suffered a near miss that caused moderate damage.^[20]

American losses were heavy; 2,403 personnel and bystanders were killed, 18 ships were damaged or sunk, and 188 aircraft were destroyed. In contrast, the Japanese lost 29 aircraft and five midget submarines.^[22] The Japanese judged the attack as a success, believing that they accomplished their primary tactical goal, which was the destruction of the battle line of the U.S. Pacific Fleet.^[5] The Japanese operations to conquer Southeast Asia and establish to a defensive perimeter could proceed without interference, and the U.S. Navy was unable to launch a major trans-Pacific counteroffensive for two years.^[5] However, the two American carriers were at sea at the time of the attack and Pearl Harbor's oil storage, dry dock, submarine piers and maintenance facilities were left unscathed.^[23] Additionally, contrary to the planned shattering of American morale, forcing the U.S. government to seek a compromise peace with Japan, the enormous loss of life and property from the sneak attack led to a tidal wave of outrage by the American public.^[5]

First operational phase

To the surprise of the Japanese, the First Operational Phase went according to plan with extremely light losses. No ship larger than a destroyer was sunk.

The last major operation of the First Operational Phase was the

The ease with which the Japanese accomplished their initial objectives led to the severe underestimation of the enemy and the resultant failure to concentrate the IJN's superior forces at key places and times.[26] As a result, the critical months of May and June 1942 saw the IJN lose both its offensive power and the initiative.^[26] The Second Operational Phase was planned to expand Japan's strategic depth by adding eastern New Guinea, New Britain, the Aleutians, Midway, the Fiji Islands, Samoa, and strategic points in the Australian area.^[27] However, the Naval General Staff, the Combined Fleet, and the Imperial Army, all had different views on the next sequence of operations. The Naval General Staff advocated an advance to the south to seize parts of Australia, however, the Imperial Japanese Army declined to contribute the forces necessary for such an operation,^[27] which quickly led to the abandonment of the concept. The Naval General Staff still wanted to cut the sea links between Australia and the United States by capturing New Caledonia, Fiji, and Samoa. Since this required far fewer troops, on March 13 the Naval General Staff and the Army agreed to operations with the goal of capturing Fiji and Samoa.^[27] The Second Operational Phase began well when Lae and Salamaua located on eastern New Guinea were captured on March 8. However, on March 10, American carrier aircraft attacked the invasion forces and inflicted considerable losses. The raid had major operational implications since it forced the Japanese to stop their advance in the South Pacific. This was to be the last of the uninterrupted victories for the Japanese until the Combined Fleet provided the means to protect future operations from American carrier attack.^[27]

In April 1942, the

Yamamoto thought it essential to complete the destruction of the United States Navy that had begun at Pearl Harbor.

The attack on Port Moresby was codenamed the MO Operation and was divided into several parts or phases. In the first, Tulagi would be occupied on May 3. The carriers would then conduct a wide sweep through the Coral Sea to find and attack and destroy Allied naval forces, with the landings conducted to capture Port Moresby scheduled for May 10.^[30] The MO Operation featured a force of 60 ships led by the two carriers: Shōkaku and Zuikaku, one light carrier (Shōhō), six heavy cruisers, three light cruisers, and 15 destroyers.^[30] Additionally, some 250 aircraft were assigned to the operation including 140 aboard the three carriers.^[30] However, the actual battle did not go according to plan, although Tulagi was seized on May 3. The following day, aircraft from the American carrier Yorktown struck the invasion force.^[30] For the next two days, both the American and Japanese carrier forces tried unsuccessfully to locate each other. On May 7, the Japanese carriers launched a full strike on a contact reported to be enemy carriers, but this report turned out to be false. The strike force found and struck only an oiler, the Neosho and the destroyer Sims.^[31] The American carriers also launched a strike on incomplete reconnaissance. Instead of finding the main Japanese carrier force, they only located and sank the Shōhō. On May 8, the opposing carrier forces finally found each other and exchanged strikes. The 69 aircraft from the two Japanese carriers succeeded in sinking Lexington and damaging Yorktown. In return the Americans damaged Shōkaku. Although Zuikaku was left undamaged, aircraft losses to Zūikakū were heavy and the Japanese were unable to support a landing at Port Moresby. As a result, the MO Operation was cancelled.^[32] Although they managed to sink a carrier, the battle was a disaster for the IJN. Not only was the attack on Port Moresby halted, which constituted the first strategic Japanese setback of the war, all three carriers that were committed to the battle would now be unavailable for the operation against Midway.^[33]

Midway

Yamamoto perceived Operation MI, the capture of Midway, as the potentially decisive battle of the war which could open the door for a negotiated peace favorable to Japan.

Aside from Mikawa's initial reaction, the Japanese were slow to respond, seeing the American landings as a reconnaissance-in-force, but by mid-August they had assembled four battleships, five carriers, 16 cruisers, and 30 destroyers to dislodge the Americans. On August 24–25, the IJN launched an operation intended to send a small transport convoy to the island and also to destroy any American naval vessels in the area. The ensuing Battle of the Eastern Solomons was the third carrier battle of the war. The IJN achieved neither of their goals, with the convoy diverted to the Shortland Islands and the American navy still present. Japanese losses were heavy, with 75 carrier aircraft, a light carrier, a transport, and a destroyer lost. ^[46] Although the American carrier Enterprise was damaged, she managed to elude Japanese attempts to sink her. With the Americans' Henderson Field on Guadalcanal now operational, convoys of slow transports could not go near the island without great risk. Consequently, until the airfield was suppressed, Japanese reinforcements were most-often delivered by inefficient destroyer runs to the island by night.^[46]

By early September, destroyers had delivered 6,200 troops for an attack on the American perimeter,^[47] but the Japanese had underestimated American forces on the island, assuming there were only 2,000 Marines: the actual number was about 20,000. The attacks launched by the Japanese on the nights of September 12–14 therefore failed. The Japanese did better in the struggle for control of the waters around Guadalcanal. On September 15, the submarine I-19 sank the carrier Wasp, leaving only a single American carrier, the Hornet, active in the Pacific.^[47] But although the Japanese possessed up to six operational carriers during the same period, they failed to capitalize on the opportunity.^[47]

By now the Japanese realized that Guadalcanal was a pivotal contest,^[47] so for the next offensive an entire Army division was assigned, with plans to get it to Guadalcanal by mid-October for an offensive beginning October 20. To support this effort, the Combined Fleet stepped up night runs by destroyers and high-speed seaplane carriers (which carried the soldiers' heavy equipment) to Guadalcanal, and a transport convoy was assembled. Aerial bombardment of Henderson Field would be intensified, and surface warships would bombard the airfield. Admiral Yamamoto now defined the Combined Fleet's primary mission as supporting the recapture of the island, with destruction of the US Pacific Fleet a secondary objective.^[47] On the night of October 13–14, the battleships Kongō and Haruna bombarded the airfield on Guadalcanal with 918 14-inch (36 cm) rounds, destroying over 40 aircraft and putting the airfield temporarily out of commission.^[47] (Mark Stille notes that despite Japan's prewar preoccupation with a titanic clash of battleships, this was the most successful Japanese battleship operation of the war.^[47]) The convoy arrived during the night of October 14–15, preceded by two heavy cruisers which shelled the airfield. Aircraft from two carriers flew cover over the transports. American aircraft succeeded in sinking three of the six transports, but not before a total of 4,500 men had landed along with two-thirds of their supplies and equipment.^[47] The Japanese kept up the pressure with another cruiser bombardment on the night of October 15–16 and more reinforcement destroyer runs. After several delays, the Japanese began the offensive on October 24. The main attack finally commenced on the night of October 25–26, but the attacks on Henderson field were repulsed by the Marines with heavy losses.^[48]

Santa Cruz

Concurrently with the Army's offensive on Guadalcanal, the IJN planned their largest naval operation to date in order to counter and defeat any American naval forces operating in support of the Marines on Guadalcanal.

The battle for Guadalcanal reached a crescendo in November. After the victory at Santa Cruz, the Japanese were sure that the naval balance in the south Pacific had swung in their favor.^[50] They planned a more substantial effort to reinforce the island. A similar plan to the one conducted in October was put forward, with a larger convoy preceded by another bombardment by battleships to neutralize the airfield. The Japanese were prepared to employ sufficient forces to guarantee its success. On the night of November 12–13, a force of two battleships, Hiei and Kirishima, one light cruiser and 11 destroyers departed for Guadalcanal to bombard the airfield. However, this attempt was thwarted by a smaller American force of five cruisers and eight destroyers, which intercepted the Japanese force. A vicious night action ensued at close range.^[50] Losses were heavy on both sides, but the critical bombardment of the airfield never occurred.^[50] Hiei was damaged and the following day was sunk by American aircraft, becoming the first Japanese battleship to be lost in the war.^[50] The Japanese then attempted another bombardment with a force centering on the battleship Kirishima, with support from two heavy cruisers and two destroyer squadrons. The IJN had additional battleships that were available, but were not employed.^[50] On the night of November 14–15, this attempt was again met by the American force which included two battleships, Washington and South Dakota. In another vicious night battle, the Japanese were again turned back, losing the battleship Kirishima during the first battleship duel of the Pacific War.^[50] These two night battles became known as the First and Second Naval Battles of Guadalcanal. They were the decisive events of the campaign.^[50] While the Americans had delivered large numbers of additional troops to Guadalcanal, the Japanese only delivered 2,000 troops and an insignificant amount of supplies.^[50] Additionally, the large Japanese convoy had lost all ten transports, which had been sunk by American aircraft from the undamaged airfield.^[50] Naval losses were heavy for both sides; the Americans lost two cruisers and seven destroyers and many ships had been severely damaged. The Japanese lost two battleships, a heavy cruiser, and three destroyers. The Japanese had been defeated more by a failure to mass their forces rather than by being outfought.^[50] The attrition suffered by the Japanese during the battles for Guadalcanal was too great. On January 4, the Navy Section of the Imperial General Headquarters instructed Yamamoto to prepare the withdrawal of the remaining troops from Guadalcanal.^[50] The evacuation of Guadalcanal was codenamed Operation Ke.^[50] The Americans detected the preparations for the operation and believed they were actually for another Japanese attempt to reinforce the island. The evacuation was carefully planned to take place in three destroyer lifts and would begin in late January 1943.^[50] The first operation was conducted with 20 destroyers on February 1, another with 20 destroyers was conducted on February 4. A third and final operation was conducted with 18 destroyers on February 7.^[51] Operation Ke was successful and 10,652 men, were evacuated from Guadalcanal, with Japanese losses only being a single destroyer.^[51]

Central Solomons and New Guinea

With Guadalcanal lost, the Japanese focus shifted to the Central Solomons and New Guinea. However, during the

An opportunity for a decisive battle came in June 1944, when the Americans landed on Saipan in the Marianas. The Japanese responded with their largest carrier force of the war, the nine-carrier Mobile Fleet, led by Shōkaku, Zuikaku, and the new armored-deck aircraft carrier Taihō. The resulting clash, the largest carrier battle in history, did not turn out as the Japanese had hoped. Instead, it ended in near-total defeat and the virtual end of their carrier force.^[57]

On June 19, a series of Japanese carrier air strikes were shattered by strong American defenses. The same day, Shōkaku was hit by four torpedoes from the submarine Cavalla and sank with heavy loss of life. Taihō, the most modern carrier, was also sunk due to a single torpedo hit from the submarine Albacore. Late the next day, the Japanese were subjected to American carrier air attack, suffering the loss of several ships, including the carrier Hiyō.^[55] The four Japanese air strikes had involved 373 carrier aircraft, of which only 130 returned.^[58] More aircraft and their crews were lost when Taihō and Shōkaku were sunk. After the second day of the battle, Japanese losses were 3,000 dead, three carriers, two fleet oilers, more than 400 carrier aircraft, and around 200 land-based aircraft, plus damage to several ships. The Americans suffered the loss of 109 dead, 123 aircraft (80 of which ran out of fuel returning from the strike on the Japanese fleet), and bomb damage to the battleship South Dakota.

Although this defeat was severe in terms of the loss of the fleet carriers Taihō, Shōkaku, and Hiyō, the real disaster was the annihilation of the carrier air groups.^[59] These losses to the already-outnumbered IJN were irreplaceable. The IJN had spent the better part of a year reconstituting their carrier air groups. The Americans destroyed 90% of that airpower in two days, leaving the Japanese with only enough aircrew to form an air group for one light carrier, returning home with 35 of about 450 aircraft with which the Mobile Fleet had begun the battle.^[55]

Demise of the Imperial Japanese Navy (1944–1945)

Leyte Gulf

Even after the disaster at Philippine Sea, the IJN was still a formidable force. Of the 12 battleships that were available at the beginning of the war in 1941–42, nine still remained operational, together with 14 out of the original 18 heavy cruisers.^[55] However, efforts to rebuild the carrier force were unsuccessful since the training given to new aviators was of a very low standard. Consequently, the new Unryū carriers never went to sea with a full air group. This left the Japanese with a ragtag collection of carriers, led by Zuikaku, which was the sole survivor of the Pearl Harbor attack force. The Japanese were left with two choices: either commit their remaining strength in an all-out offensive, or sit by while the Americans occupied the Philippines and cut the sea lanes between Japan and vital resources from the Dutch East Indies and Malaya. The plan devised by the IJN was a final attempt to create a decisive battle using its last remaining strength, the firepower of its heavy cruisers and battleships, which were to be all committed against the American beachhead at Leyte. The Japanese planned to use their remaining carriers as bait, in order to lure the American carriers away from Leyte Gulf long enough for the heavy warships to enter and destroy any American ships present.

The Japanese assembled a force totaling four carriers, nine battleships, 13 heavy cruisers, seven light cruisers, and 35 destroyers.^[60] The main Center Force would pass through the San Bernardino Strait into the Philippine Sea, turn southwards, and then attack the landing area. Two separate groups of the Southern Force would strike at the landing area through the Surigao Strait, while the Northern Force with the carriers was to lure the main American covering forces away from Leyte.^[60] However, the carriers only embarked just over 100 aircraft, the equal to those on a single American fleet carrier; the Japanese were risking annihilation. The situation in 1944 revealed the weakness of the IJN. After departing from Brunei Bay on October 20, the Center Force was attacked by two American submarines which resulted in the loss of two heavy cruisers with another crippled. On the night of October 24–25, the Southern Force, consisting of the two Fusō-class battleships escorted by a heavy cruiser and four destroyers, attempted to enter Leyte Gulf from the south through Surigao Strait. This action was fought at night, where an American force of six battleships, eight cruisers, 28 destroyers, and 39 PT boats ambushed the Japanese.^[61] Utilizing radar-guided torpedo attacks, American destroyers sank one battleship and three destroyers while damaging the other battleship. Naval gunfire finished off the second battleship and the heavy cruiser, with only a single Japanese destroyer surviving. Another group, part of the Southern Force, was built around two heavy cruisers. This force failed to coordinate its movements with the first and subsequently arrived at Surigao Strait in the middle of the encounter, made a haphazard torpedo attack, and retreated.^[61]

That day, after entering the Sibuyan Sea, the Center Force was assaulted by American carrier aircraft throughout the whole day, forcing another heavy cruiserto retire. The Americans then targeted Musashi and sank her under a barrage of torpedo and bomb hits. Many other ships of the Center Force were attacked, but continued on.^[60] Convinced that their attacks had made the Center Force ineffective, the American carriers headed north to address the newly detected threat of the Japanese carriers. Off Cape Engaño, the Americans launched over 500 aircraft sorties at the Japanese force, followed up by a surface group of cruisers and destroyers. All four Japanese carriers were sunk, but this part of the Leyte plan had succeeded in drawing the American carriers away from Leyte Gulf.^[61] On October 25, the final major surface action fought between the Japanese and Americans fleets during the war occurred off Samar, when the Center Force fell upon a group of American escort carriers escorted by only destroyers and destroyer escorts. Both sides were surprised, but the outcome looked certain since the Japanese had four battleships, six heavy cruisers, and two light cruisers leading two destroyer squadrons. However, they did not press home their advantage, and were content to conduct a largely indecisive gunnery duel before breaking off. In exchange for the loss of three heavy cruisers, Center Force sank a single escort carrier and three escorts. Losses were extremely heavy with four carriers, three battleships, six heavy cruisers, four light cruisers and eleven destroyers sunk. This represented a total of 305,452 tons or 13.22 percent of the total Japanese warship tonnage losses during the war.^[62]

After Leyte Gulf, the IJN was finished as an effective force. The IJN was left with six battleships Hyuga, Ise, Nagato, Haruna, Kongo and Yamato; five fleet carriers Junyo, Shinano (never operational), Amagi, Katsuragi and the Unryu; the light carrier Ryuho; the escort carriers Kaiyo and Shinyo; the training carrier Hosho; eight heavy cruisers Aoba, Ashigara, Haguro, Myoko, Nachi, Takao, Kumano and Tone; nine light cruisers Kitakami, Kiso, Isuzu, Kashima, Kashii, Yahagi, Sakawa, Oyodo and the Yasoshima; and some twenty destroyers plus escorts, minesweepers, and patrol vessels.^[63]

Last Sortie

American forces

Japan continued to attribute considerable prestige to

The second half of World War II saw the last battleship duels. In the

Thanks to the Japanese carriers' successfully decoy role, the

Ultimately, the maturity of air power spelled doom for the battleship. Battleships in the Pacific ended up primarily performing shore bombardment and anti-aircraft defense for the carriers. Only the fast battleships (formerly battlecruisers) of the Kongo class saw much action due to their speed, while the slower and heavier battleships were held in reserve for a decisive engagement of battleships versus battleships which never happened. Yamato and Musashi were sunk by air attacks long before coming in gun range of the American fleet.^[67]

Aircraft carriers

In the 1920s, the Kaga (originally laid down as a battleship) and a similar ship, the Akagi (originally laid down as a battlecruiser) were converted to aircraft carriers (航空母艦 Kōkūbokan) to satisfy the terms of the Washington Naval Treaty.^[68] From 1935 to 1938, Akagi and Kaga received extensive rebuilds to improve their aircraft handling capacity.^[68]

Japan put particular emphasis on

Japanese World War II destroyers (駆逐艦 Kuchikukan) included some of the most formidable destroyers of their day. This came as a nasty surprise to the Allies, who had generally underestimated Japanese technical capabilities. The Japanese had reassessed their naval needs in the mid-1920s and, placing an emphasis on ship and weapons technology and night fighting expertise, developed a completely new destroyer design. Subsequent development from one destroyer class to the next was not, however, a smooth progression. Aside from the usual changes arising from experience, serious design faults also came to light and naval treaties imposed restrictions. As a result, the early "Special Type" destroyers required significant changes and the specifications of subsequent classes was reduced in one way or another. Naval treaties were later abrogated in 1937 and so destroyer development continued without regard to limits.

Generally speaking, the Imperial Japanese Navy (IJN) requirements gave rise to warships that were substantially larger than their European or American equivalents, often well-equipped with heavy torpedo armament for surface engagements but with less emphasis on anti-aircraft or anti-submarine armament. In the early war years, their advantages were exploited against the often second rate and poorly coordinated Allied ships stationed in the region such as at the IJN victory in the Battle of the Java Sea. The Japanese did not, however, continue to install new technology, such as radar, to match their opponents, and destroyer numbers were eroded steadily in the latter half of the Pacific War. The Japanese emphasis on capable but expensive fleet destroyers had neglected the need for large numbers of cheaper escort vessels (destroyer escorts or frigates) to defend critical merchantmen, a need learnt by both the Royal Navy and the United States Navy in the Battle of the Atlantic. In recognition that quantity was as important as quality in some roles, design policy was therefore modified to produce units that were easier to build and operate. Despite this, Japan's destroyer force was halved by the end of the war. The survivors were given to the Allies.

Naval aviation

Japan began the war with a highly competent naval air force designed around some of the best airplanes in the world: the

Japan had by far the most varied fleet of

Early models were not very maneuverable under water, could not dive very deep, and lacked radar. Later in the war, units fitted with radar were in some instances sunk due to the ability of US radar sets to detect their emissions. For example, USS Batfish sank three such in the span of four days. After the end of the conflict, several of Japan's most innovative and advanced submarines were sent to Hawaii for inspection in "Operation Road's End" (I-400, I-401, I-201 and I-203) before being scuttled by the U.S. Navy in 1946 when the Soviets demanded access to the submarines as well.^[83]

Special Attack Units

At the end of

A considerable number of Special Attack Units were built and stored in coastal hideouts for the desperate defense of the Home islands, with the potential to destroy or damage thousands of enemy warships.[85]

Navy Land Forces