Okinawa

Okinawa is the largest and most important of the Ryukyu Islands between Japan and Formosa. It is some 64 miles (103 km) long and two to eighteen miles (3 to 30 km) wide, with a total area of 640 square miles (1660 km²). The northern two thirds of the island is quite rugged, with elevations to 1500' (460 meters), and heavily forested, with a single one-lane road. The area from the small port of Naha south has coral ridges reaching to 500' (150 meters), but the area north of Naha had considerable flat ground suitable for airfields and barracks, making the island the natural staging area for the final invasion of Japan. However, the road network was mostly one-lane roads and trails, only a fraction of which were surfaced with crushed coral, and all of which were underlain by clay soil that was incapable of sustaining heavy military traffic in rainy weather.  This was supplemented by about thirty miles (50 km) of narrow-gauge railroad linking Naha to Kadena airfield and other points in the south of the island. Two of the three railroads on the island were horse-drawn rather than locomotive-driven.

Much of the coastline is coral cliffs with numerous coral heads. However, the coastline west of Kadena had a coral reef 200-700 yards (180-640 meters) offshore that could be crossed by trucks at low tide. This was the area chose by the Americans for their landings, both because of the suitability of the beaches and because the Kadena and Yontan airfields, located just 2000 yards (1830 meters) inland, could be quickly seized to help provide fighter cover for the invasion fleet. The Americans dubbed these the Hagushi beaches after a small village located approximately on the boundary between the Army and Marine sectors. Nakagusuku Bay on the southeast of the island, which the Americans later renamed Buckner Bay, also had some suitable landing beaches. The Japanese were aware of this and centered a heavy artillery fortress regiment here.

The climate is characterized by moderate temperatures (40F or 4C winter lows, 85F or 29C summer highs) and high humidity. Rainfall averages 93" (236 cm) per year with bulk arriving from May to September.

The native Okinawan culture in 1941 more strongly resembled Chinese than Japanese culture in customs and architecture, which created friction with Japanese administrators and servicemen sent to the island. Okinawa had no history of warfare, and its people practiced an animistic religion centered on ancestor worship. The island was dotted with lyre-shaped stone tombs containing urns with human remains inside, and there were also numerous nature shrines (utaki) often centered on a sacred stone (ibe).

The island had a population of about 435,000 in 1945. The great majority of these lived in the southern third of the island, four-fifths of which was farmland producing sweet potatoes, sugar, rice, and soybeans. About 60,000 children and 20,000 other civilians were evacuated by ship, and another 60,000 relocated in the rugged north away from the anticipated battleground in southern Okinawa. Of those that remained, some 100,000 are estimated to have perished in the Okinawa campaign, where some 25,000 were conscripted into the Army and others murdered by the Japanese when they got in the way (Drea 2009).

During the evacuation, a transport, likely unmarked, was sunk by an American submarine with the loss of 700 school children. The other 186 vessels involved in the evacuation were unscathed.

In addition to the two main airfields at Yontan and Kadena, there was a smaller airfield (Machiano) just north of Naha, an abandoned airfield (Yonabaru) east of Machiano, a Navy airfield on Oroku Peninsula south of Naha, and two airfields on Ie Shima.

Some fifteen miles (24 km ) west of the southern end of Okinawa one finds the Kerama Retto, a group of small, hilly islands about 7 by 13 miles (11 by 21 km) with a maximum elevation of 787' (240m). The terrain is unsuitable for airfield construction but the islets surround a deep protected anchorage. This was capable of accommodating 75 large ships and its two entrance channels could be easily defended with nets. There was also a suitable location for seaplane operations in Aka Channel.

The Okinawa Campaign

Preliminaries. American planning for the Okinawa campaign began with a preliminary study by Nimitz' staff dated 25 October 1944. Capture of the island was seen as an alternative to seizing Formosa, and would provide the Allies with a staging area close to Kyushu for the final invasion of Japan. Final planning began on 24 November 1944 between Reifsnider, who would the amphibious group commander; Turner, who commanded the Pacific Fleet's amphibious forces; Buckner, commander of 10 Army, which would constitute the invasion force; and Geiger, commanding III Amphibious Corps, the Marine component of 10 Army. Other top American commanders included Hall, who would command the Army's amphibious group, and Blandy, who would command the support forces, and Deyo, commanding the bombardment force. The invasion as a whole would come under the command of Spruance and 5 Fleet.

The plan to take Okinawa was risky and audacious. Okinawa was 800 miles (1290 km) from the nearest Allied airfields, which meant the invasion would be almost completely reliant on carrier air cover. The invasion force would be within easy kamikaze range of both Formosa and Kyushu, and Allied intelligence estimated that the Japanese could concentrate up to 3000 aircraft against the landings. Nimitz wanted B-29 support against the kamikaze airfields, but this was bitterly resisted by Curtis LeMay as an unacceptable diversion from their strategic bombing role. (A public relations officer on LeMay's staff later claimed that LeMay wanted to send a message to Hap Arnold demanding Nimitz' court-martial for obstructing the war effort.) However, Nimitz succeeded in getting two B-29 missions flown against the kamikaze airfields, on 29 and 31 March. These badly damaged the airfields, and simultaneous aerial mining of Shimonoseki Strait closed the strait for a week.

Carrier strikes had already begun the softening-up process, with the first strikes being launched against Kyushu on 18 March 1945. American pilots encountered few Japanese aircraft in the air or on the ground, although scout planes discovered a concentration of warships (including Yamato) in the Inland Sea. The Japanese had detected the American raid and had their aircraft dispersed or in the air; 50 were committed to immediate kamikaze strikes, which succeeded in lightly damaging Enterprise and Yorktown. American strikes the next day damaged seventeen Japanese warships in the Inland Sea, but none seriously. Japanese counter strikes inflicted moderate damage on Wasp and very nearly destroyed Franklin, which was hit when its hangar was full of planes warming up for a strike. A series of at least six secondary explosions left her flight deck resembling "a half-eaten Shredded Wheat biscuit" (Morison 1959) and inflicted casualties of 724 killed or missing and 265 wounded. Expert damage control allowed her to return to New York for repairs, but these were not completed before the Japanese surrender.

As the force withdrew on 20 March, destroyer Halsey Powell was hit by a kamikaze that missed Hancock and inflicted moderate damage. The next morning, the Japanese launched a final attack by 48 aircraft, including "Betty" bombers carrying Oka suicide aircraft. The raid was intercepted 60 miles (100 km) out and the heavily laden "Bettys" proved easy prey for the Hellcats.

By 23 March the carriers were in position to launch its final series of raids on Okinawa itself. The Japanese, who greatly overestimated the damage done by their kamikazes and were hampered by damaging B-29 raids to their airfields on 29 and 31 March, were slow to react, and serious kamikaze attacks around Okinawa did not begin until six days after the first landings. This final series of carrier raids included thorough photoreconnaissance, which hinted just how tough an objective Okinawa might prove to be. The reconnaissance revealed "that the entire island was a honeycomb of caves, tunnels and gun positions" (Morison 1959) and that armored vehicles had been spotted taking cover in cave entrances. Mitscher forwarded this information to Turner on 26 March along with reassurances that Task Force 58 would provide all possible air cover.

On 24 March Mitscher launched a strike of 112 aircraft against a convoy spotted 150 miles (240 km) northwest of Okinawa. The entire convoy of eight ships was sunk.

The preliminary naval bombardment under Blandy and Deyo began on 25 March 1945 and lasted a full eight days. The bombardment force included ten older battleships, seven heavy cruisers, three light cruisers, 24 destroyers, eight destroyer escorts, and 53 landing craft converted to rocket or mortar ships. The bombardment would ultimately expend 3,000 aircraft sorties, 13,000 battleship and cruiser shells, and millions of smaller projectiles. Its chief effect on the Japanese troops was to raise their morale by increasing their confidence in the strength of their fortifications. However, it likely killed tens of thousands of unprotected civilians and leveled all but one of the buildings in Naha.

The naval bombardment was accompanied by extensive mine sweeping operations in the waters around the island. By the time of the landings, the minesweeper force had swept 184  mines from six separate fields n an area of 2500 square miles (6500 km²). During these operations, destroyer Halligan hit a mine that set off her forward magazines and destroyed the ship. Casualties were 153 killed and 39 wounded out of 325 crew. Skylark hit two mines that sank her on 28 March, though with slight loss of life. Minelayer Adams was crippled by a kamikaze on the day of the landings. The minecraft, which had to operate independently or in small groups and lacked point defenses, eventually suffered over 15% of naval casualties in the campaign.

Local air cover during the bombardment was provided by 18 escort carriers (Durgin) while the fast carriers of 5 Fleet struck at distant airfields that might stage aircraft against the bombardment force. However, shortly after dawn on 27 March, before the American combat air patrol had formed up, a group of seven kamikazes attacked the bombardment force, inflicting moderate damage on Nevada and light damage on Biloxi. Destroyer O'Brien was severely damaged and forced out of the campaign while minesweeper Dorsey took light damage. Another Japanese raid on the night of 28 March was directed against small patrol craft and sank LSM(R)-188. Thereafter the escort carriers flew dawn interdiction sweeps against local Japanese airfields that put an end to the dawn raids.

As the bombardment continued, Allied intelligence officers puzzled over reports from spotting aircraft and other observers that there was almost no sign of Japanese activity anywhere on the island. Intelligence officers remained concerned about the possibility of enfilading fire from caves in limestone bluffs overlooking and from pillboxes constructed around the airfields and along the high sea wall (6'  to 7' or 1.8m to 2.1m) behind the beaches. The final phase of the bombardment attempted to knock out these positions while creating breaches in the sea wall, but with little success.

On 31 March a final attack by four kamikazes succeeded in crippling Spruance's flagship, Indianapolis. Spruance transferred his flag to New Mexico.

Total ammunition expenditure in the week before the landings was 1033 16" (406mm) shells, 3285 14" (356mm) shells, 567 12" (305mm) shells, 3750 8" (203mm) shells, 4511 6" (152mm) shells, and 27,266 5" (127mm) shells.

Kerama Retto. The main landings were preceded by the seizure of the Kerama Retto on 26 March by 77 Division (Bruce). Turner had seized on the idea of seizing the anchorage to serve as a safe haven for damaged warships during the campaign. The idea initially received a very cool reception from staff officers concerned about the lack of air cover, but Turner insisted on the operation, and the anchorage proved very useful during the Okinawa campaign. The landing force was brought ashore by Kiland, who planned simultaneous landings in force on five of the six largest islets. It was believed that 1000 to 1500 Japanese troops were on the islands, but this proved an overestimate. 

Bombardment for this smaller operation began on 26 March and was carried out by Joy with two cruiser and three destroyers. Underwater demolition teams (UDTs) reconnoitered the proposed landing beaches the same day, finding that the beaches on the two outermost islands were unsuitable for anything but LVTs. Since none could be spared, these two landings were postponed. 

The remaining landing operations encountered no opposition as the defending Japanese troops had fled into the hills. Two counterattacks that night were repelled at a cost to the Japanese of 106 dead. On Geruma Shima, the Americans found twelve women and a number of children strangled by their own men, who had been worked into a terror of the Americans by Japanese propaganda.

The landings on Kerama Retto were covered by strikes against Miyako Retto by the British carriers of Task Force 57, which had just reported to Pacific Fleet, and local combat air patrol was provided by three American escort carriers. However, nine kamikaze broke through to attack the landing force the evening of the landings, lightly damaging destroyer Kimberly.

Another kamikaze threat was neutralized by the Kerama Retto invasion: A landing force directed against suspected coastal batteries (which turned out to be a sugar mill) discovered over 250 small motor boats in heavily camouflaged caves and hangars. Sometimes described as suicide boats, these craft were 18' (6m) long and carried a single pilot and two 250-pound (113 kg) depth charges. The charges could be dropped next to an Allied ship and would take long enough to sink that the motor boat theoretically might get away, so that their mission was not strictly a suicide mission, however remote the chances of survival. A perfunctory attack on net tender Terebinth on 28 March was carried out by a boat whose pilot dropped the charges 50' (15 m) from his target, inflicting damage on neither. Six more boats were destroyed by gunfire over the next two days. A boat battalion commander was captured and proved surprisingly cooperative, giving his interrogators a chart of the Japanese plans to attack any landing force off Okinawa with the boats.

Total casualties in the Kerama Retto campaign were 145 Americans killed or missing and 211 wounded, the majority of them sailors. The Japanese lost about 530 killed and 121 taken prisoner. Some 300 Japanese remained at large in the hills of the Kerama Retto until the final Japanese surrender.

Main landings. On 29 March Mitscher took up position some 120 miles (190 km) south of Kyushu to launch fighter sweeps against Japanese airfields and provide combat air patrol for the invasion forces gathering around Okinawa. The next day a preliminary landing by 155mm artillery from XXIV Corps took place on Keise Shima, a group of four islets seven miles (11 km) west-northwest of Naha, where they could help provide fire support for the main landings. There was no significant opposition.

Also on 30 March, the escort carriers launched a large raid against Unten Ko, a small cove on the east coast of Motobu Peninsula where photoreconnaissance had detected a nest of midget submarines. Meanwhile the UDTs began demolishing beach obstacles, which consisted mostly of wooden anti-boat stakes.

American forces began landing on Okinawa itself at 0800 on April Fool's Day (1 April) 1945. The initial landings were by elements of 1 and 6 Marine Divisions of III Amphibious Corps and 7 and 96 Divisions of XXIV Corps (Hodge). The Marines landed on the northern half of the landing area, while the Army divisions landed to their south. Their immediate objective was the Yontan and Kadena airfields, which were to be quickly put into service to provide land-based air coverage.

The Japanese had anticipated the landings on Okinawa, which was part of their inner defense zone defined in the "Outline of Army and Navy Operations" promulgated on 20 January 1945. Besides Okinawa, the major strong points in this zone were Iwo Jima, Formosa, Shanghai, and southern Korea. The garrison of Okinawa consisted of 77,000  troops of 32 Army (Ushijima), supplemented by about 20,000 local Okinawan conscripts. The Japanese sent no further reinforcements to Okinawa after the start of 1945. On the contrary, part of 32 Army had been redeployed to Luzon in December 1944. The remainder of 32 Army was built around 24 and 62 Divisions, 44 Independent Mixed Brigade, and 27 Tank Regiment. Much of the artillery intended for the Philippines remained on Okinawa, and some 3200 veteran gunners were organized into 5 Artillery Command. The result was that the Americans on Okinawa would be targeted by the largest concentration of Japanese artillery of the Pacific War.

Resistance was initially very light, and the American forces reached the airfield at Yontan by 0956 and Kadena by 1035. Both were secured by evening. It was later claimed that the Marines encountered only 15 Japanese in the entire III Amphibious Corps sector. The first patrols reached the east coast of Okinawa on 2 April and were firmly established across the waist of the island by 4 April.

III Amphibious Corps now turned north and continued encountering only light resistance as they approached the Motobu Peninsula. XXIV Corps had already turned south, and 96 Division hit the Japanese rearguard on 2 April. The rearguard was quickly overcome, but by 5 April the Army troops were approaching the main Japanese defense line, the Shuri Line, and by 8 April the rapid advance had come to an abrupt halt. On that date, 6 Marine Division was facing stiff resistance in the Motobu Peninsula, while XXIV Corps found itself up against the main Japanese defensive line around Shuri and was on the receiving end of the heaviest Japanese artillery fire of the Pacific War.

The initial light resistance reflected a new Japanese tactical doctrine of shūgettsu ("bleeding strategy") which had first been deliberately applied on Iwo Jima. This tactical doctrine acknowledged no hope of repelling the invaders and sought instead to inflict such casualties on the casualty-averse Americans that they would hesitate to invade the home islands. The Army had released a tactical manual, "Essentials of Island Defenses," in August 1944 which emphasized mobile defense anchored at strong points and conducting local counterattacks. Dispersal and concealment were emphasized, and defense on the beach deemphasized in the face of massive American fire support. In accordance with this doctrine, Ushijima deployed only two battalions in the northern two-thirds of the island. However, shūgettsu went against a generation of Japanese training that emphasized offensive operations, and even the Emperor questioned why the airfields on Okinawa had been given up so easily. 10 Area Army ordered a counterattack to retake the airfields, which were desired for kamikaze operations, but Ushijima ignored the order.

Death Ride of Yamato. On receiving word of the landings on Okinawa, Toyoda activated Ten-go, the contingency plan for an attack on Japan's inner defense perimeter. Ten-go called for 4500 aircraft to be concentrated against the American invasion fleet to cover a sortie by the remaining surface strength of the Japanese Navy. Because of the desperate fuel situation, the surface force would only have enough fuel to reach Okinawa, where the ships were ordered to beach themselves to act as giant armored coastal batteries. Since the average Japanese pilot skill was so poor by this point in the war, there would be no attempt to provide air cover for the surface force. Instead, all available aircraft would be thrown against the American carrier force in hopes of distracting the Americans sufficiently to let the surface force get through.

Allied code breakers were able to give warning of Ten-go and both submarines and patrol aircraft were waiting for the Japanese sortie. At 1745 on the evening of April 6, submarine Threadfin sighted superbattleship Yamato, escorted by light cruiser Yahagi and eight destroyers, exiting the Inland Sea via the Bungo Suido. In accordance with orders, the submarine radioed the sighting rather than attacking at once. The Japanese task force steered far to the west in a vain effort to stay out of the operational radius of aircraft from the American carriers east of Okinawa, but were spotted by American search aircraft at 0823 on 7 April. Deyo promptly maneuvered his force to stay between the Japanese and the American landing beaches, and at 1000 Mitscher launched a strike of 280 aircraft, including practically every available torpedo bomber (98 in all.) Hancock's aircraft got lost on the way to the target, and Radford's task group launched a smaller second strike, 106 aircraft, about fifteen minutes after the first strike.

The American aircraft was spotted by Yamato at 1232, and the entire force put up fierce antiaircraft fire, but by 1241 Yamato had received her first two bomb hits. The first torpedo hit came four minutes later. The first wave continued attacking until 1417, putting another five torpedoes into the battleship. Counterflooding failed to correct the list, the ship lost power on three of her four shafts and rapidly lost speed, and additional torpedoes and at least ten more bomb hits smothered her. By 1420 the list had increased to 35 degrees, and at 1423 she slid under, accompanied by a number of spectacular explosions.

The remaining ships of the force were also hit hard. Yahagi took an impressive 12 bomb hits and seven torpedo hits before going down. Destroyer Hamakaze was sunk and three more destroyers were scuttled after being heavily damaged. Four destroyers from the force managed to escape to Sasebo. Japanese casualties were 3665 killed and 209 wounded; the Americans lost just 10 aircraft and 12 aircrew.

Breaking the Shuri Line. On 8 April, following the sinking of Yamato, Turner signaled Nimitz that "I may be crazy but it looks like the Japs have quit the war, at least in this section." This reflected a general air of unrealistic optimism among the Allies. Nimitz was more skeptical, and signaled back "Delete all after 'crazy'!" Nevertheless, while 27 Division was ashore by 10 April, Turner ordered 2 Marine Division back to Guam to relieve shipping congestion.

Resistance stiffened as the Americans moved south, and XXIV Corps soon encountered deeply entrenched Japanese troops in the coral ridges dominating the southern half of the island. The ridges cut across the island and restricted fields of fire, reducing the American superiority in firepower. The Japanese strong points included pillboxes with steel doors that proved highly resistant to flamethrowers, the usual weapons used to reduce Japanese fortifications. The Japanese also sometimes took cover in the numerous stone tombs peculiar to the indigenous culture. The campaign degenerated into static warfare that has been likened to the battle of Verdun in the First World War. A notable feature of the battle was that, for once, the Japanese had ample fire support. Japanese artillery once fired 14,000 shells on XXIV Corps in a single twenty-four hour period. 

Meanwhile III Amphibious Corps continued mopping up northern Okinawa. On 14 April, patrols from 6 Marine Division reached the north point of Okinawa, but encountered stiff resistance in the Motobu Peninsula, which was defended by 2000 troops and was not cleared until 1 May.  At 0758 on 16 April elements of 77 Division landed on Ie Shima. The Americans encountered stiff resistance around Iegusuga volcano (607' or 185 meters), likened by some observers to Mount Suribachi on Iwo Jima, and the island was not secured until the evening of 21 April. Casualties were 172 Americans dead and 902 wounded. The dead included the famed journalist Ernie Pyle, who was caught by a burst from a machine gun.

Ushijima was persuaded by offensive-minded members of his staff to launch two major counterattacks during the battle. The first, on the evening of 12 April, achieved a modest penetration of the American lines, but the three battalions responsible for the penetration were then cut to ribbons, two being wiped out and only half the men from the third making it back to the Japanese lines. The Americans responded with a push by three divisions on 19 April. The American attack was preceded by a massive bombardment, but in spite of 19,000 rounds of shell fire from 27 artillery battalions, the attack was stopped cold by Japanese defenders whose deep fortifications remained largely undamaged. However, by 23 April, Ushijima ordered a withdrawal from his forward positions to his strongest defense line, centered on Shuri Castle. The withdrawal was covered by fog and artillery and was not detected by the Americans until the next morning.

The second counterattack, on 4 May, was a massive effort involving the best troops from all three divisions and timed to coincide with the fifth kikusui operation (see below). It was launched at dawn with the support of the most massive artillery barrage by the Japanese in the Pacific War, which placed about 12,000 shells on the American positions. The main attack was preceded by night counter landings behind both American sea flanks. However, the western counter landing force became disoriented in the darkness and came ashore too far south, running directly into the Marine line instead of behind it, and was annihilated with the help of LVT(A)s. The eastern force was sighted by warships and driven back into the sea by the reconnaissance troop from 7 Division. The main dawn attack fared no better. Only a single battalion broke through the American front, and the offensive was called off after a day and a half.  Japanese casualties were about 7000 dead. Four days later the Americans laid a massive barrage on Japanese positions as a celebration of the surrender of Germany.

The low point of the campaign was reached with torrential rains that began on 16 May. These continued with little letup until the end of the moth and greatly increased the misery of the troops on the ground.

The island might never have been secured by the Americans had it not been for the lack of cohesion among the Japanese defenders. Many officers were unhappy with shūgettsu and insisted on carrying out local counterattacks that simply allowed the Americans to make good use of their massive firepower. Most the Japanese formations had been cobbled together, and battalion commanders often failed to tie their defenses into neighboring battalions. As a result, the Americans became increasingly proficient at infiltrating the Japanese lines at unit boundaries. For the first time in the Pacific War, the Japanese were forced to feed replacements directly into the line, and observers on both sides noted that the Japanese infantry became increasingly reluctant to reveal their positions by firing in support of neighboring positions manned by soldiers they hardly knew.

The Japanese line finally began to crack in late May. On 27 May Naha fell, and the Shuri line finally collapsed on 29 May. The loss of Shuri was a devastating blow to Japanese morale, and the retreat south nearly turned into a rout. Wounded men were abandoned as their comrades sought the relative safety of the final defensive line, and, for the first time in the Pacific War, significant numbers of Japanese troops began to desert. The Japanese were gradually driven into a small pocket in the southwest corner of the island, which was raked by increasingly concentrated American fire as the pocket shrank. Large numbers of Okinawan civilians, terrified of falling into American hands, were caught up in the retreat and experienced indescribable suffering. 

Not all the Japanese joined the retreat. Admiral Ota and about half of his naval infantry chose to disobey Ushijima's order to abandon the Oroku Peninsula, which was taken by elements of 6 Marine Division. These landed on the peninsula early on 4 June and had captured the main position, Admiral's Hill, by 13 June.

On 19 June Ushijima issued his final orders calling for resistance to the end. Organized resistance ended two days later, and at 0300 on 22 June Ushijima and his chief of staff committed ritual suicide. By then the Americans had already lost their own commander: On 18 June, Buckner was killed by Japanese artillery fire while at a forward observation post.

Buckner was widely criticized for failing to use his own artillery effectively and for rejecting proposals for a second amphibious landing in the Japanese rear, at Nakagasuku Bay, by the reserve division (2 Marine Division).

The Kamikaze Battle. While the land battle raged, an equally deadly air and sea battle raged offshore. Initially air resistance was light, but the pattern for the future was foreshadowed on the evening of the landings, when a number of kamikazes attacked West Virginia and inflicted light damage. Most of the kamikazes went after Wright's decoy force off the southeast of Okinawa, damaging LST-884 and transport Hinsdale. Transport Alpine and cargo ship Achernar were also hit and moderately damaged but were able to unload their undamaged cargo before leaving for repairs. The supporting carrier aircrew were not trained for night operations and had to return to their carriers before dusk settled in. This produced a window of vulnerability for the fleet, and many of the most deadly kamikaze attacks took place at twilight and were directed against the radar picket destroyers whose task was to detect incoming raids. 

Turner initially planned to pull the transports away from the beaches at night to leave them less vulnerable to attack, but on 3 April he observed the transports making smoke as they took up position and concluded that the improved capability for generating smoke screens made the ships safer close to shore than at sea. Turner also instituted an elaborate screening plan with no less than six layers of screening vessels around the core of the fleet. The outermost were the picket destroyers, which were stationed at specified points 15 to 100 miles (24 to 16 km) out. Each had a fighter director team on board and a section of fighters assigned as combat air patrol. Within the picket screen was an anti-surface patrol of destroyers covering likely approaches to Okinawa.Still further in was a "flycatcher" screen, mostly of LCI gunboats reinforced with a small number of destroyers and light cruisers, whose function was to watch for motor torpedo boats, "suicide" boats, or other small craft. The fourth layer was an outer antisubmarine screen, while the fifth was a radar countermeasures screen composed of LCIs. The final layer was the inner antisubmarine destroyer screen.

Small raids on 2-5 April 1945 succeeded in sinking a fast transport and an LCI. The kamikazes also damaged a transport and three landing ships badly enough to knock them out of the campaign, and another five ships, including battleship Nevada, took less serious damage. But the Japanese were just getting warmed up.

It was a rule of thumb among experienced Allied naval officers that the Japanese took about four days from the day of a landing to organize a concerted air counterattack, but poor weather on 5 April gave the Americans a reprieve. 6 April saw the beginning of the largest and costliest kamikaze attack of the war, the first of ten kikusui ("floating chrysanthemum") attacks launched as part of Ten-go. While Toyoda was unable to concentrate the hoped-for 4500 aircraft against the American invasion fleet, he had 699 aircraft, including 355 kamikazes, available on 6 and 7 April 1945. Some 182 of these aircraft broke through the American defenses to attack the invasion force. These succeeded in sinking three destroyers, two cargo ships, a landing ship and two minecraft, wrecking beyond repair another three destroyers and a destroyer escort, and knocking battleship Maryland, two destroyers, a transport, and a minecraft out of the campaign. Another six warships were badly damaged. Total casualties on the sunk or damaged ships were 485 killed and 582 wounded. The American combat air patrol claimed 310 Japanese aircraft shot down, and another 41 were claimed by antiaircraft fire.

Allied casualties might have been even worse but for the work of the Allied code breakers. Their warnings of a second attack on 11 April were widely disseminated (the cover story being that the warning had come from a talkative captured Japanese pilot) and Mitscher ordered all carrier attack aircraft disarmed, defueled, and stowed away while the fighters were concentrated for local defense. Meanwhile Spruance, concerned by the terrible vulnerability of the picket destroyers, requested expedited delivery of replacement aircraft and pilots. The second kikusui attack began to develop at 1330 on 11 April and sank or badly damaged another eleven warships over the next two days. These included Spruance's flagship, Tennessee. Enterprise was lightly damaged but returned to full operations within 48 hours. During the second kikusui, the Japanese introduced the Ohka, dubbed baka ("crazy") by the Allies, and a baka sank destroyer Mannert L. Abele.

Notwithstanding the signals intelligence, Allied intelligence estimates were that the Japanese had shot their bolt with the second kikusui attack. In addition, by 8 April, 82 Marine Corsairs on MAG-31 and MAG-33 were based on Yontan along with seven night fighters, with more aircraft on the way. (Some 3521 fighter sorties would be flown from the fields by 1 May.) Officers who had been through kamikaze attacks in the Philippines observed that the individual effectiveness of the kamikazes was not as great, and attack statistics tend to bear this out. However, some destroyer commanders had concluded that nothing short of a 5" shell could reliably stop a kamikaze, and that lone destroyers on picket duty without twilight fighter cover were sitting ducks. The night fighters would not have their radar gear installed and calibrated before 14 April; and if the kamikazes had lost some of their individual effectiveness since the Philippines, they were much more numerous.

Although the most numerous and damaging attacks of the campaign were by kamikazes, there were a number of conventional air attacks as well, including a torpedo plane attack on the night of 12 April. As was their practice, the Japanese dropped pyrotechnics just before the attack ("the brightest flares that anyone on board had ever witnessed" according to Morison 1959) and Deyo immediately ordered a turn to evade. No torpedo struck home, but two exploded in the wakes of Tennessee and Idaho. Another conventional torpedo attack on 16 June hit Twigg in a magazine and sank the ship. "Suicide" boats also participated in the campaign, but proved largely ineffective, and large numbers were destroyed. Conventional submarines were almost completely ineffective and four were sunk by the Allies.

The Allies struggled to find an adequate response to the kamikazes. After April 10, the more exposed picket stations were assigned two destroyers and four LCS. However, by the time the fleet had suffered its fifth kikusui attack, there were clear signs of deteriorating morale, particularly among the crews of the picket destroyers. By May 16, radar stations were operating on Ie Shima and Hedo Saki and the number of picket stations could be reduced to five. Task Force 58 launched strikes on Kyushu on 15-16 April 1945, achieved surprise, and claimed to have shot down 29 aircraft and destroyed 51 aircraft on the ground, which likely reduced the strength of Kikusui 3 significantly. However, the Japanese had become skilled at dispersing their aircraft over the many small airfields available on the home islands.

The sixth kikusui cost the Americans the services of Bunker Hill, which was hit by two kamikazes that set ablaze aircraft parked on the flight deck. Though the ship was saved, casualties were very heavy (396 dead or missing and 264 wounded) and repairs were not completed before the Japanese surrender. The Americans responded with strikes on Kyushu on 13-14 May that put the kamikazes largely out of business for the next ten days, but at the cost of Enterprise, damaged badly enough that she, too, did not return to the Pacific before the war was over.

Kikusui 7 was marked by some changes of tactics on the part of the Japanese, suggesting that they, too, were feeling the strain of the campaign. The strangest was the raid on Yontan airfield on the night of 24 May by a group of five Ki-21 "Sallys" loaded with fifty suicide raiders. The first Sally achieved surprise and was able to crash-land on the airfield, and its ten passengers managed to kill two Americans and wound another 18, destroy seven aircraft and damage 26 others, and blow up 70,000 gallons of gasoline. The subsequent four Sallys were all shot down with their passengers.  

The seventh kikusui also was notable for largely ignoring the picket destroyers and concentrating on the bombardment and transport forces. Fast transport Barry was wrecked and, though still afloat, judged beyond economical repair. The hulk was later towed out to be a decoy for later kamikazes, a desperate tactic (which nonetheless worked; Barry  was sunk on 21 June, along with her towing vessel.)

Further evidence of Japanese exhaustion came with the 10th kikusui, which was relatively ineffective. A pilot of a Ki-61 "Tony" was shot down directly over an American destroyer, and, to the astonishment of the American observers, the pilot attempted to bail out. Ironically, his parachute failed to open completely and he perished anyway. American exhaustion was exemplified by the loss of Porter, which was lost when a near-miss by a kamikaze caused flooding from the underwater shock that could not be controlled because the aft portion of the ship was not properly "buttoned up." On the other hand, the skill of the fighter directors and CAP at picket station 15 allowed the American fighters to claim 40 Japanese aircraft without the two destroyers at the station having to fire a single antiaircraft round.

At one point, the Joint Chiefs of Staff authorized the diversion of B-29s away from strategic missions to attack the kamikaze airfields, which did reduce the severity of the attacks somewhat. 

One indication of the nature of the campaign is the ammunition expenditure through 20 May 1945:

High-capacity shells, used for bombardment, were expended in great numbers, but their expenditure is dwarfed by that of 5"/38 antiaircraft shells. Expenditure of star shells (illuminating rounds) was also notably high. In addition to the naval ammunition expenditures, Marine Corsair squadrons dropped some 152,000 gallons of napalm during the campaign.

Curiously, Beary's service force, stationed in the open sea 200 miles south of Okinawa, was rarely attacked during the campaign. This was consistent with a Japanese predisposition to ignore logistics, their own and the enemy's.

In addition to the 1465 kamikaze sorties in the main kikusui attacks, the Japanese launched a number of individual attacks that brought the total kamikaze sorties to about 1900 in number. The Japanese Navy reported a total of 3700 sorties, including conventional sorties, and the Army likely added half again as many sorties to the total.

Consequences of the Battle. The mere fact of the Americans successfully coming ashore on Okinawa brought about the fall of the Koiso cabinet, with the Prime Minister resigning on 4 April.

On the other hand, the Japanese largely achieved the goals of their shūgettsu strategy. American combat deaths in the Okinawa campaign numbered 12,510, with about 45,000 wounded and 36,000 non-combat casualties. This was about 17% of all Navy and Marine losses in the Pacific War. Some 32 warships were sunk and another 368 damaged, and 763 aircraft were lost. About 70,000 Japanese were killed, along with 30,000 to 100,000 Okinawan civilians. An unprecedented 7,401 Japanese soldiers surrendered, though almost half of these were Okinawan conscripts. The battle of Okinawa disheartened the Allies while encouraging the Japanese. However, it was probably also a major contributing factor to the decision to drop nuclear bombs on Japan.

Japanese order of battle, 1 April 1945

Allied order of battle, 1 April 1945