The Battle of Okinawa, the largest land battle of World War II’s Pacific theater, was the conflict’s amphibious high-water mark for the number of men landed, casualties incurred, and military equipment used.1 The United States committed seven Army and Marine Corps divisions to Operation Iceberg, the seizure of the Ryukyu Islands, including Okinawa.2 Lieutenant General Simon Buckner’s Tenth Army, composed of the XIV Army Corps and the III Marine Amphibious Corps, assaulted Okinawa on Easter Sunday, 1 April 1945. The two corps faced more than 100,000 defending Japanese soldiers of the 32nd Army and supporting naval units as well as 20,000 men of the Okinawan home guard.3
In 1944, as Allied forces defeated the Japanese in the South and Central Pacific, the U.S. Joint Chiefs of Staff (JCS) and operational planners had developed three options to force Japanese full capitulation: Bomb and blockade mainland Japan into submission, increase strategic bombing followed by invasion of Kyushu and Honshu, or drop the atomic bomb.4 The Roosevelt administration and the JCS weighed the three alternatives against the cost in life and matériel.
JCS planners considered using mainland China and Formosa as bases to support the first two options to defeat Japan, but the Japanese disrupted these plans by successfully seizing air bases in China. U.S. military intelligence estimated an extremely high cost in men and matériel to defeat Japanese forces on Formosa.5 When the commander of the U.S. Pacific Fleet, Admiral Chester Nimitz, queried his service component commanders on the feasibility of seizing Formosa, General Buckner, replied that he did not have sufficient troops.6 Nimitz recommended to the JCS that Luzon, Iwo Jima, and the Ryukyu Islands should be taken before invading Formosa.7
The following day, 3 October 1944, the final decision was made to abandon the Chinese basing plans for the more suitable areas of Okinawa in the Ryukyus and Iwo Jima in the Volcano Islands. Both locations provided more direct sea lines of communication to U.S. rear areas and closer airfield locations to strike the Japanese Home Islands. The JCS determined that the revised operational plan was the most suitable alternative to support all three options for ending the war and directed Admiral Nimitz to seize the Ryukyus in March 1945.8 With the approval of Operation Iceberg, the die was cast for the eventful clash of human wills on Okinawa.
Individual Marines, soldiers, and sailors fought aggressively to sustain offensive actions on the island while Japanese defenders fought with intense tenacity to protect Emperor Hirohito and national pride and suffered more than 100,000 killed in the battle.9 Although it was destroyed, the Japanese 32nd Army nevertheless successfully accomplished its defensive mission and eventually influenced the U.S. decision to use atomic weapons to end the war. With extremely limited air support, nonexistent logistical refit, and limited force reconstitution, the 32nd Army delayed U.S. Pacific forces, engaging them in sustained combat for more than two and a half months, inflicting heavy casualties, and ultimately preventing the invasion of the Home Islands.10
Operationally the battle was a U.S. victory, but the heavy American losses influenced President Harry Truman’s advisers to recommend the use of atomic weapons. While ending World War II, the use of the new weapons ultimately started the Cold War and associated political and military posturing between countries aligned with democracy or communism.
A battle’s victors and its vanquished often will define success differently. For the U.S Marines and Army, success was seizing Okinawa, albeit at a high cost, and using the island as a forward staging base to launch attacks on the Home Islands. From the 32nd Army’s perspective, success did not depend on battlefield victory. Ultimate victory would have been the destruction of America’s power-projection ability. But to understand Japanese success on Okinawa, the problem of the 32nd Army’s mission must be understood.
Buildup to Battle
Throughout the latter part of 1944 and into 1945, Imperial Japanese Headquarters (IJHQ) constituted and reinforced the 32nd Army on Okinawa. Initially, IJHQ had ordered the 32nd to construct and protect 14 airfields throughout the Ryukyu Islands for Japanese aircraft to use in launching a decisive strike on the U.S. Central Pacific Force, either Admiral William Halsey’s 3rd Fleet or Admiral Raymond Spruance’s 5th Fleet, as it approached Japanese waters.11 But because of U.S. victories in the Central and South Pacific and the attrition of Japanese forward-deployed forces, the 32nd Army’s mission would change from simple airfield guard duty to protecting the Home Islands by vigorously defending the Ryukyus. As the army prepared for that mission, U.S. forces began to hinder its progress.
The actions of stealthy U.S. submarines continually frustrated 32nd Army commander Lieutenant General Mitsuru Ushijima. One of the first combat units assigned to Okinawa was the 44th Independent Mixed Brigade, which had fought with distinction in China and was among the Imperial Japanese Army’s “most prized units.”12 On 29 June 1944, the USS Sturgeon (SS-187), a submarine patrolling waters within the Ryukyu Islands chain, sank the transport Toyama Maru carrying the majority of the seasoned 44th Brigade and its commanding officer.13 The loss had a significant demoralizing effect on the Japanese army. The 32nd would now depend more on aircraft for troop transport and supplies, severely limiting its ability to defend the islands.
While ships carrying reinforcements for the 32nd Army were dodging U.S. submarines, the Marianas came under U.S. control with the fall of Saipan in July. Not only were Japanese troop transports and merchant shipping within Home Island waters now at the mercy of the U.S. submarine fleet, but heavy losses in the Marianas campaign caused IJHQ officers to see the reality of U.S. momentum. The 32nd Army’s defense of Okinawa became more strategically important.14
IJHQ rightly assessed that the United States would advance on the Home Islands through the Philippines, Formosa, or Okinawa.15 Japanese planners immediately marshaled ground forces toward each location in hopes of checking U.S. moves. Within months, the 32nd Army consisted of four divisions in addition to the reconstituted 44th Brigade for a total strength close to 110,000 trained Japanese soldiers.16 But to ensure a proper defense of the Ryukyus, the 32nd Army asked for a total of 180,000 troops.17 Not only did IJHQ not send additional men, but it withdrew the 9th Division to defend Formosa, weakening the 32nd Army’s strength. The original Okinawa defensive plan assigned the 9th, the most capable and experienced division in the 32nd Army, the critical task of repulsing U.S. forces as they landed on the island’s beaches.18 IJHQ intended to replace the division, but as the months passed, Japanese shipping losses and U.S. forces’ aerial dominance in the region prevented the replacement troops from reaching Okinawa.19
Despite the division’s withdrawal, General Ushijima reported his intention to defend Okinawa’s beaches. IJHQ’s response was: “We will have the decisive battle on Japan proper. Okinawa is merely a front-line action.” General Ushijima’s operations officer, Colonel Hiromichi Yahara, therefore recalled being puzzled by a message from Emperor Hirohito on the eve of the battle in which he “solemnly declared that [the Battle of Okinawa’s] outcome would determine the nation’s future.” As it turned out, once the battle was joined, the 32nd Army found itself fighting the decisive battle.20
General Ushijima clearly took to heart the emperor’s words that the defense of Okinawa was of vital importance, and the coming battle was not merely a “front-line action.” Without the 9th Division, the 32nd Army’s commander would concede the beaches to U.S. forces while defending fortified positions in the hills and valleys of the southern portion of Okinawa.21 Ushijima concluded that the 32nd Army could not defeat the Tenth Army, but it could draw the enemy into a defensive trap, bogging down U.S. ground forces in a battle of attrition.
While American Marines and soldiers would be suffering heavy losses assaulting strongly defended Japanese positions, Japan’s remaining air forces would attempt to destroy the U.S. fleet with kamikaze attacks.22 Colonel Yahara specifically described the strategy as attritional, aimed at delaying U.S. forces and inflicting maximum losses in men and matériel. Holding the Okinawa “fortress” as long as possible would give the Imperial Japanese Army more time to fortify the Home Islands and equip and train forces there for the expected U.S. invasion.23 Ultimately, the Japanese officers believed that their defense of Okinawa was a defense of their own families.
High Cost of U.S. ‘Victory’
The U.S. assault on Okinawa unfolded just as the Japanese commanders had expected, with an amphibious landing on the western beaches and the main U.S. force turning southward, right into their defensive trap.24 The Tenth Army advanced on a broad front, providing ample opportunity for the Japanese to delay the battle’s conclusion. The 32nd Army’s defense of the island, combined with kamikaze attacks on nearby warships, successfully entangled the U.S. war effort on and around Okinawa for more than two and a half months, gaining time for homeland defense preparations.25
Japanese forces on Okinawa inflicted heavy U.S. losses. With 49,151 men killed and wounded, the United States suffered the highest number of casualties in a single battle against the Japanese.26 Added to this figure is slightly more than 26,000 “non-battle” casualties, mostly victims of combat fatigue, or combat-stress disorders.27 Considering the brutality of the battle and the length of time in constant combat against an enemy who would fight to the death, it is surprising that more men did not suffer from debilitating emotional and psychological problems. Eyewitness accounts of the battle, such as Eugene Sledge’s With the Old Breed, discuss the effects of combat stress on the morale of the individual and unit.
Although unintended, the Japanese were able to affect the combat effectiveness of U.S. units through combat-fatigue attrition. The 32nd Army therefore not only inflicted losses in men and matériel but also attrited battle veterans’ ability and/or will to fight.
The Next Move
Soon after the battle, Admiral Raymond A. Spruance, whose 5th Fleet had battled Japanese forces off Okinawa’s shores, called the struggle for the island “a bloody, hellish prelude to the invasion of Japan.”28 Retired U.S. Marine Corps Colonel Joseph H. Alexander later summed up the attitude of the veterans of the battle:
In a nutshell, the plans for invading Japan specified the Kyushu landings would be executed by the surviving veterans of Iwo Jima and Luzon; the reward of the Okinawa survivors would be the landing on the main island of Honshu. Most men grew fatalistic; nobody’s luck could last through such infernos.29
The gamble for U.S. leaders and military planners was if U.S. forces would have the fortitude to endure an invasion of the main Japanese islands after the brutality of the Pacific island campaigns or if U.S. momentum would wane. Although the 32nd Army had inflicted much pain and loss on U.S. forces and delayed their advance, the unintended high rate of combat fatigue within the Tenth Army was a significant factor in future invasion planning.30
The last area of success for the 32nd Army was in protecting the Home Islands from invasion. Although the III Marine Amphibious Corps and XIV Army Corps finally destroyed the 32nd Army, and the U.S. Army Air Forces’ strategic bombing campaign of Japan had continued, American forces did not set foot on the Home Islands until Emperor Hirohito’s surrender. Leading up to Okinawa, American strategy for forcing Japan to surrender consisted of three options. After the Battle of Okinawa, U.S. forces faced approximately 2,350,000 armed men on the Japanese main islands as well as a civilian population determined to defend its homes.31 According to U.S. leaders’ rationale, if the 32nd Army with around 100,000 men could inflict such high causalities, then the cost in men, matériel, and civilian deaths would be too steep to justify additional invasions.
The Army Air Forces’ intensive bombing of Japan’s cities (including the firebombing of civilian areas) that began following the capture of the Marianas had resulted in no indications the Japanese were ready to capitulate.32 Following the Battle of Okinawa, the only remaining U.S. options to force surrender were either invasion by ground troops or use of the atomic bomb. Okinawa was certainly not the only determining factor that led to the eventual decision to drop atomic bombs on Hiroshima and Nagasaki, but the carnage inflicted by General Ushijima’s forces certainly influenced the decision.33
A single Japanese army on Okinawa, with scarce logistics resupply, negligible air support, and no reserve, delaying a large combined-arms attacking force with strong logistics support for nearly three months could certainly be considered a success. U.S. Marine and Army units next faced the even more brutal reality of an adaptive enemy defending its homeland. The result of the Battle of Okinawa therefore ultimately led to the use of atomic bombs on Hiroshima and Nagasaki and forever changed the world’s concept of strategic diplomacy.
1. Charles Sidney Nichols and Henry I. Shaw, Okinawa: Victory in the Pacific, Marine Corps Monographs (Washington DC: Historical Branch, G3 Headquarters, USMC, 1955), 269.
2. I. T. M. Gow, Okinawa, 1945: Gateway to Japan (Garden City, NY: Doubleday, 1985), 28.
3. Roy Edgar Appleman et al., Okinawa: The Last Battle, United States Army in World War II: The War in the Pacific 5–11 (Washington, DC: Center of Military History, 1993), 91.
4. Gow, Okinawa, 1945, 5.
6. Nichols and Shaw, Okinawa, 16.
7. Appleman et al., Okinawa, 4.
9. Ibid., 489. Col Joseph H. Alexander, USMC (Ret.), The Final Campaign: Marines in the Victory on Okinawa (Washington, DC: History and Museums Division, Headquarters, U.S. Marine Corps, 1996), 51. Battle of Okinawa sources differ on casualty numbers for Japanese forces because of inaccurate accounting in both Japanese and U.S. battle reports. Japanese sources report approximately 76,000 killed, but only show a force of 77,000 at the beginning of the battle. Appleman et al. report 16,000-plus Japanese POWs recovered by October 1945. Suffice to argue Japanese forces suffered a 90–95 percent KIA.
10. Gordon Warner, The Okinawa War (Kumoji Naha City, Japan: Ikemiya Shokai, 1985), 201.
11. Hiromichi Yahara, The Battle for Okinawa (New York: J. Wiley, 1995), 3.
12. Ibid., 12.
13. Ibid., 31. Robert J. Cressman, The Official Chronology of the US Navy in World War II (Annapolis, MD: Naval Institute Press, 2000), 239.
14. Yahara, The Battle for Okinawa, 13–15.
16. Gow, Okinawa, 1945, 32.
17. Yahara, The Battle for Okinawa, 15.
18. Ibid., 31–32.
19. Ibid., 29.
20. Ibid., 46.
21. Appleman et al., Okinawa, 92–93.
23. Yahara, The Battle for Okinawa, 32, 49.
24. Ibid., xii.
25. Appleman et al., Okinawa, 6.
26. Ibid., 473.
27. Warner, The Okinawa War, 201.
28. Alexander, The Final Campaign, 51.
30. Gow, Okinawa, 1945, 214–15.
31. Ibid., 209.
32. Ibid., 211.
33. Ibid., 215.