The Battle of Okinawa (April to June 1945) was the largest amphibious assault and last major battle of the Second World War (1939-45). A massive naval fleet landed 170,000 US troops on the island, but it took two and a half months of bitter fighting to defeat a Japanese army determined to inflict as many casualties as possible on the enemy by whatever means possible. Around 100,000 Japanese combatants, up to 150,000 civilians, and around 12,000 US troops were killed on Okinawa. Victory gave the US the perfect platform from which to launch an assault on Japan's largest islands, an operation made unnecessary by the dropping of two atomic bombs and Japan's surrender in August 1945.
The Pacific War So Far
The Japanese military government had built an impressive empire for itself, which, by 1941, spread from northern China to the Solomon Islands. In December 1941, Japan, seeking to crush its enemy before it had a chance to even enter the war, launched the infamous attack on Pearl Harbor, the US naval base in Hawaii. The US responded powerfully, sending its navy to the Battle of the Coral Sea in May 1942, winning the Battle of Midway the following June, freeing the Solomon Islands in the Guadalcanal Campaign (August 1942 to February 1943), and following all that up with another victory in the Gilbert and Marshall Islands Campaign (November 1943 to February 1944).
The US forces had been 'island-hopping' across the Pacific, each time using a captured island group to build a new base from which another amphibious advance could be made. Japan went on the defensive. US forces targeted the Mariana Islands in the Battle of Saipan (Jun-Jul 1944) and the Battle of Guam (Jul-Aug). Moving ever closer to the Japanese home islands, the next major encounter came at the Battle of Iwo Jima (February to March 1945). In the bloodiest battle of the Pacific War (for the US), the US forces suffered 27,000 casualties but managed to take the island. Iwo Jima became an important base for fighters to escort Boeing B-29 Superfortress bomber squadrons as they repeatedly hit Tokyo and other Japanese cities. The next target was Okinawa in the Ryukyu Islands; the mission to take it was code-named Operation Iceberg.
Okinawa
The island of Okinawa is located 340 miles (550 km) from the main islands of Japan but was then (and still is) considered part of Japan itself. It is the main island of the Ryukyu group and measures around 60 miles (96 km) in length. In 1945, the local population stood at around 500,000. The terrain of the island was ideal for a prolonged defence: many peninsulas, rocky ridges, deep ravines, rivers, caves, and patches of jungle.
If US forces could capture and operate from the airstrips on Okinawa, they would be able to strike repeatedly at Japanese cities and provide vital air cover if it should become necessary, which looked increasingly likely, to launch an invasion of the four main Japanese islands of Honshu, Hokkaido, Kyushu, and Shikoku.
Okinawa was a much larger island than those previously taken in amphibious assaults in the Pacific War. The planned assault was comparable in size and complexity to the D-Day operation in Europe in June 1944. Indeed, the operation was bigger than the Normandy landings in terms of the fleet size and troops landed in the first stages of the assault. Over 500,000 US service personnel were involved and 1,213 warships, not including the large British Pacific Fleet, which also participated. The mass of warships was indeed formidable and demonstrated beyond doubt the industrial might of the US. Included were 40 aircraft carriers, 18 battleships, and 200 destroyers.
The first task was to take the nearby Kerama archipelago, an operation which secured a safe haven for US ships and aircraft damaged in the coming battle for Okinawa. The naval fleet, supported by aircraft, then bombarded Okinawa for eight days prior to the amphibious landing. 13,000 naval shells were fired at the island, and bombers performed 3,000 sorties. In Naha, the capital, only one building survived the bombing. Demolition frogmen, meanwhile, removed as many obstacles as possible that the defenders had laid down to obstruct the approach to the beaches.
The Defence
The defence of Okinawa was made up of at least 80,000 members of the 32nd Japanese Army and a militia force of Okinawans numbering around 20,000, a force which included children. Many local girls were obliged to work as medical staff, even if this exposed them to the same bombs and gunfire as the combatants had to endure.
In command of the Japanese army on Okinawa was Lieutenant-General Ushijima Mitsuru. Ushijima believed that kamikaze pilots would best disrupt the invasion on the beaches while his main land force would defend the island's interior, especially Naha. The Motobu peninsula was also heavily defended. Aware that victory was unlikely, Ushijima was determined to hold out as long as possible and exact a terrible price in casualties from the invaders.
The Japanese regular units had all been bulked up with far more weaponry – especially anti-tank guns, grenade launchers, and heavy machine guns – than was typical in the Japanese army. Even irregular units such as sailors who no longer had a ship to operate or pilots and ground crews whose aircraft were no longer airworthy managed to cobble together all kinds of improvised weaponry, ranging from automatic naval cannons to fighter-plane machine guns. In contrast, the militia of Okinawans, a sort of Home Guard, was poorly armed and many of these had to settle for antiquated rifles or even spears made from sharpened bamboo (still an unpleasant enough weapon to meet in dense jungle).
The Landings
The initial US attack was, as expected, overwhelming. 16,000 US troops were landed in the first hour, 60,000 on the first day. LVTs (Landing Vehicles, Tracked) zipped through the shallows with their human cargoes while simultaneously firing at the enemy with their machine guns and 75-mm (3-inch) howitzers.
Four divisions of the new 10th US Army landed on the southwest beaches of Okinawa on 1 April 1945; these were the 1st and 6th Marine divisions and the 7th and 96th Infantry divisions. Another three divisions would land on Okinawa as the invasion progressed. In all, 170,000 US troops attacked the island. Most of these soldiers were young men, as here described by Marine Lenly Cotton:
Our platoon was – other than the one that could vote – they were all under twenty. Ninety per cent were nineteen or younger, there were as many below eighteen as above, five or six that were sixteen, including myself, and one that was fifteen that I know personally.
(Holmes, 483)
Following the troops onto the beaches were Sherman tanks. Here a lesson was learned from the D-Day operation, as flotation devices were welded onto the sides of the tanks to ensure they could make their own way through the shallows to land. The idea was not entirely successful since some tanks sank anyway and others took hours to reach the beaches. Still, the steady addition of armour provided the Marines with much-needed support.
The US forces quickly took over the two airfields of Kadena and Yontan, and they had made significant inroads into the island stronghold by 4 April. As in earlier island operations, the US troops expertly combined flamethrowers, bulldozers, and explosives to clear out bewildering mazes of underground tunnels and bunkers, as well as the enlarged caves the island's defenders had dug out of the coral stone, most of which had proved impervious to the bombardment prior to the landings.
The most difficult area of progress was in the northern part of the island. Here the defences were densely arranged and included many caves. One Japanese tactic was to ensure well-camouflaged gun positions protected each other. As a consequence, US troops concentrating on taking an enemy position ahead of them often came under withering fire from their flanks. Snipers were everywhere, too, especially in positions which protected comrades manning a heavy gun behind them. Snipers often hid in covered holes in the ground the Japanese called 'octopus pots' since they resembled the cooking pots used for that delicacy.
The Battle at Sea
Meanwhile, on 6 April, the Japanese counterattacked at sea. The First Mobile Fleet, which included the giant battleship Yamato, attacked the Allied fleet off the coast of Okinawa. The Japanese fleet was destroyed by the vastly superior Allied force. The Battle of the East China Sea was the last major air-sea battle of WWII. Amongst the various horrors of the battle was the sinking of the Yamato and loss of 3,000 men with it.
A serious threat remained to the Allied fleet. Over the course of the Battle of Okinawa, around 1,900 kamikaze suicide attacks were made on the Allied ships. These attacks most commonly took the form of now more or less obsolete Mitsubishi A6M Zero fighters flown by inexperienced pilots. It was hoped that if enough shipping were sunk, the Allied fleet would withdraw, and so the troops on Okinawa would be denied vital air support and logistical backup. Some motor launches filled with explosives were also used in kamikaze strikes. As US fighter defences became ever sharper and anti-aircraft guns began using special explosive rounds, kamikaze attacks became much less effective, their success rate in this battle being only around 15%.
There was one variation on the kamikaze theme introduced at the Battle of Okinawa. The Baka bomb was a small aircraft propelled by a rocket system (but still piloted to its target by a human), which contained a nose packed with 1,800 lbs (816 kg) of explosives. The name Baka, which was the US nickname using a Japanese word for this device, translates as 'idiot'. The Japanese themselves gave these suicide machines the more poetic name of ohka ('cherry blossom') or jinrai ('thunderbolt'). In the end, only one ship was sunk by a Baka bomb.
The Desperate End
By 20 April, US forces had taken control of the southern part of the island and the Motobu peninsula. Civilians had been encouraged to give themselves up using loudspeakers and promises they would not be harmed. Through May, Ushijima fought each defensive line as best he could, and then withdrew to another line of defences further north. The defenders, believing surrender dishonourable, often fought to the death. Even when soldiers surrendered, they very often blew themselves up with a grenade, sometimes trying to take with them an enemy soldier or two. There were countless cases of self-sacrifice where a US Marine threw himself on a grenade to smother the blast and protect his comrades in arms.
Even civilians tried to commit suicide rather than surrender, perhaps because they had been indoctrinated to believe they would be tortured and killed anyway if captured. One such tragedy, where hundreds of civilians threw themselves off a cliff, was witnessed by the war correspondent Robert Sherrod:
It was the great crowning horror of all the sights, something we never believed could happen even though we'd seen suicide attacks before. But the useless destruction of babies and children – some people threw their children over the cliff and then jumped after them – was something that was horrid for the Western mind to comprehend.
(Holmes, 496)
Naha surrendered on 27 May. Ultimately, the Japanese forces were hemmed into their last defensive line across the Oroku peninsula. It took a month to break through this final position and claim total victory. Ushijima committed suicide on the day the island finally fell: 22 June.
The Battle of Okinawa resulted in up to 100,000 Japanese combatants killed and up to 150,000 civilians killed. Around 12,000 US troops were killed and approximately 38,000 wounded (National Museum of the Pacific War). An additional 25,000 US soldiers suffered from 'battle-stress' (Holmes, 482). Only 7,400 Japanese combatants survived to become prisoners of war (Dear, 653). 4,900 Allied naval personnel were killed and 4,824 wounded. The material losses were high, too. The Allies lost 36 naval ships and landing craft while 368 were damaged. 763 aircraft were lost in the battle.
Final Victory
The Japanese military, even if persistently losing its battles, continued to inflict unacceptably heavy casualties on US forces, around 35% (when in other theatres of the war 10% was considered dangerously high). The possession of Okinawa, ideal for new US air and naval bases that could attack the main Japanese islands, "tended to make all campaigns fought to the south strategically irrelevant" (Horner, 64). Major campaigns ongoing in the Philippines and South Asia would shortly be overshadowed by events in Japan itself. A planned invasion of Kyushu in November, with predicted US casualties of around 250,000, was rendered unnecessary by the terrible destruction of Hiroshima and Nagasaki in August using nuclear bombs, which, at last, brought Japan's surrender. The Battle of Okinawa had proved to be the final major battle of the Second World War.