Tip of the Iceberg: Okinawa 1945 and Lessons for Island Battles

  • Published
  • By Christopher L. Kolakowski


This article examines the Battle of Okinawa in 1945 and draws lessons relevant to a potential future invasion to capture Taiwan. An overview of Operation Iceberg outlines the massive assault by U.S. forces to seize Okinawa from entrenched Japanese defenders over 91 days of combat. Three key lessons emerge: (1) ground forces are paramount, requiring full naval and air support until objectives are secured; (2) airpower dominance decides the offshore battle for surface supremacy; (3) nearby land bases are essential for staging, sustaining, and reinforcing the invasion. While not a replay of past battles, a hypothetical Taiwan campaign would likely feature similar operational challenges as Okinawa involving complex joint operations, need for air supremacy, undersea warfare, and disputes over vital offshore islands and bases. As a seminal Pacific battle, Okinawa's harsh lessons merit thorough analysis by modern planners and strategists.



The US Naval Institute's American Sea Power Project recently tasked a group of authors with projecting a potential invasion of Taiwan in 2026. Notably, several contributors drew parallels from World War II for insights and lessons. Retired Captain William Toti pointed out that a conflict over Taiwan “is not a repeat of Midway. It is Okinawa in reverse, with the United States on the defending side and China attacking with ten times the landing force that went ashore on Okinawa.”[1]

Operation Iceberg, the successful invasion of Okinawa, unfolded from 1 April to 2 July 1945. It stands as the bloodiest encounter in the Pacific War and holds the distinction of being the largest sea-air-land battle in history. The operation involved more than 1,500 vessels of various types and 183,000 personnel from the US Tenth Army, later reinforced to over 250,000. Over the course of three months, US ground forces suffered 7,374 fatalities, 31,807 wounded, and 239 missing in action. Naval losses added another 4,907 killed and 4,824 wounded, totaling 49,151 casualties. The invasion fleet encountered 36 ships sunk and 368 damaged during the same period. Japanese defenders numbered 120,000, with casualties exceeding 110,000 military personnel killed and over 7,000 taken prisoner, along with the destruction of more than 7,000 aircraft and 16 vessels. Okinawa's civilian population suffered more than 82,000 casualties, including suicides.[2]

For both adversaries, the battle for Okinawa served as a full-dress rehearsal for a potential invasion of the Japanese home islands. Many observers regarded the engagement as the pinnacle of amphibious warfare. As Marine lieutenant general Roy E. Geiger stated, “most clearly that our basic principles of tactics and technique are sound, are ‘in the book,’ and need only be followed in combat.” It stands as the most recent large-scale amphibious battle in the Pacific, offering valuable insights into past and potential island conflicts in the region.

This article will analyze the progression of the Okinawa campaign, followed by an examination of its primary lessons for planners and strategists.

The Battle of Okinawa: Overview

Operation Iceberg's objectives centered on the Ryukyu Islands, a prefecture of Japan and the closest territory to Japan's home islands targeted in military operations thus far. Okinawa and its adjacent islands lay approximately 350 miles from Kyushu, the southernmost of Japan's home islands, placing them well within the operational range of Japanese land-based aircraft. Additionally, these islands were approximately equidistant from Japanese bases in Shanghai and approximately 500 miles from Japanese airfields in Formosa. In stark contrast, the nearest American bases were situated 900 miles away in Leyte or 1,200 miles distant in the Palaus and the Marianas. Honolulu and Pearl Harbor lay 4,100 miles to the east of Okinawa, with San Francisco a further 2,100 miles beyond.[3]

Okinawa, the largest and most densely populated island in the Ryukyu chain, spanned approximately 60 miles along a primarily north-to-south axis, with widths varying from two to 18 miles. While certain areas boasted flat terrain, particularly in the island's central region, much of Okinawa featured rolling landscapes adorned with frequent woodland. The majority of the island's 400,000 inhabitants resided in its southern third, which encompassed Okinawa's two largest urban centers, Naha and Shuri. Throughout the middle and southern regions of the island, potential airfield sites were scattered.

Operation Iceberg outlined a comprehensive three-phase strategy for the conquest of Okinawa and its surrounding environs. Initially, Phase I focused on securing southern Okinawa, succeeded by Phase II, which targeted the island's northern third and the adjacent Ie Shima. Phase III followed, subdivided into stages IIIa through IIId, with the aim of capturing additional islands situated farther north. Subsequent to each phase's completion, the acquired territory would undergo development to serve as a base for forthcoming operations. The overarching objective was to accommodate an air force comprising 650 aircraft, along with providing anchorages for shipping necessary to support an invasion of the Japanese home islands. Anticipated completion of all objectives was set within a period of 120 days.

Figure 1. The Ryukyu Islands. (Source: US Army)

LTG Simon Bolivar Buckner, Jr., US Army, assumed the pivotal role of senior ground commander for Operation Iceberg in his capacity as Commanding General of Tenth Army. Under Buckner's command were a composite force comprising both US Army and US Marine Corps units. The Army contingent included LTG John R. Hodge's XXIV Corps, comprised of MG Archibald V. Arnold's 7th Infantry Division and MG James L. Bradley's 96th Infantry Division, alongside MG Andrew D. Bruce's 77th Infantry Division. Additionally, MG George Griner's 27th Infantry Division stood in floating reserve, with MG Paul Mueller's 81st Infantry Division available upon request to ADM Chester W. Nimitz. Spearheading the Marine contingent was LtGen Roy Geiger's III Amphibious Corps, composed of MajGen Pedro del Valle's 1st Marine Division, MajGen Thomas L. Watson's 2nd Marine Division, and MajGen Lemuel Shepherd's 6th Marine Division.

Island governance and development fell under the purview of an Island Command (ISCOM), led by MG Fred C. Wallace, US Army. Operation Iceberg also entailed the establishment of a dedicated land-based air force centered around the 2nd Marine Aircraft Wing, designated as the Tactical Air Force (TAF) and under the command of Marine MajGen Francis Mulcahy. Both ISCOM and TAF operated under the jurisdiction of Tenth Army, thereby endowing General Buckner with a broader spectrum of responsibilities than any preceding Pacific field army commander.[4] 

Supporting Tenth Army were the 1,500 vessels comprising ADM Raymond Spruance’s Fifth Fleet, tasked with providing logistical and protective backing for Buckner's operations. VADM Richmond K. Turner, US Navy, directed all amphibious maneuvers and coordinated the multiple task forces responsible for transporting ground forces to Okinawa. Initially, Buckner reported to Spruance and Turner during the initial phases of the battle, later transitioning to direct accountability to Nimitz. The overarching joint planning emanated from Nimitz's headquarters, with meticulous coordination between Buckner's and Turner's staffs on the tactical details. The collaborative relationships established prior to the landing proved instrumental during the ensuing battle.

The final tactical plan for Operation Iceberg outlined Tenth Army's deployment of 183,000 personnel from Hodge's and Geiger's corps for the landing at Hagushi on Okinawa's western shoreline on 1 April 1945. A week preceding the primary assault, Bruce's division would secure the nearby Kerama Retto as a fleet anchorage. Concurrently, Watson's division would stage a demonstration off Minatoga on Okinawa's southeastern coast to divert enemy attention. Subsequent to the Hagushi landings, Tenth Army would undertake a concerted effort to traverse Okinawa and bifurcate the island, a task anticipated to span up to 15 days. Following this phase, XXIV Corps would execute Phase I, encompassing the capture of Okinawa's southern third. Under Buckner's directives, III Amphibious Corps and other available units would launch an offensive against northern Okinawa and its adjacent islands as part of Phase II. The subsequent operations in Phases IIIc and IIId (with Phases IIIa and IIIb omitted during planning) would witness three divisions from V Amphibious Corps and one from Tenth Army seizing Miyako and Kikai Islands further to the north. Admiral Nimitz would dictate the sequencing and timing of Phase III assaults.

Figure 2. The plan of attack. (Source: US Army)

Opposing Buckner on Okinawa was Lieutenant General Ushijima Mitsuru’s Thirty-Second Army, established in 1944 as part of Japan's broader strategy to prepare for a final confrontation on the home islands, with Okinawa serving as a strategic stronghold. “The objective was . . . to smash U.S. endeavors to move aerial and naval bases forward, and to carry out overall operations,” recalled Colonel Hayashi Saburo of Imperial General Headquarters (IGHQ). “In other words, the execution of a decisive struggle in the homeland was to be facilitated . . . IGHQ felt that there were two keys to success in the Okinawa campaign: Proper and effective aerial operations; and prevention of the establishment of an American beachhead.”[5]

Ushijima commanded a formidable force comprising two divisions, a brigade, a tank regiment, Okinawan militia, and attached units, totaling 120,000 men. Opting for a strategy aimed at maximizing delay and inflicting damage upon US forces, Ushijima elected not to mount a defense directly on the beaches, instead enticing Buckner's troops to venture inland for a decisive confrontation. Most of Ushijima's forces were strategically positioned within a series of fortified defense rings centered around Shuri, with additional detachments stationed in central and northern Okinawa. The intent was to draw Buckner's army deeper into Ushijima's prepared defenses, thereby setting the stage for decisive counterattacks and eventual victory.

American intelligence succeeded in gathering substantial information regarding Ushijima's preparations and gained a fundamental understanding of Okinawa's topography. However, deficiencies existed in two critical areas. Firstly, detailed maps encompassing the entirety of Okinawa were lacking. Secondly, assessments of Ushijima's troop strength underestimated his numbers, attributing between 60,000 and 70,000 men to him—a miscalculation that persisted until the latter stages of the battle.

On 26 March, Bruce's 77th Infantry Division launched an assault on Kerama Retto, successfully securing the island group in just over four days with minimal casualties. On 1 April 1945, Tenth Army initiated its landing operation on Okinawa, with the invasion date designated as L-Day, or "Love Day," utilizing the phonetic alphabet of the era—an ironically chosen appellation that sparked considerable commentary.

Upon landing, American forces encountered minimal resistance as they advanced inland. A private from the 7th Infantry Division encapsulated the sentiments of many when he remarked, “I’ve already lived longer than I thought I would.” By nightfall, troops from Tenth Army had made significant strides across the island, achieving in 24 hours what had been anticipated to require several days. Reflecting on the swift progress, Buckner felt fortunate, “The Japs have missed their best opportunity on the ground and in the air,” mused Buckner to his diary. “When their counter-attack comes we will be holding strong ground.”[6]

On 3 April, Buckner signaled to Geiger, “All restrictions removed on your advance northward.” Buckner's decision to initiate Phase II ahead of schedule demonstrated notable initiative and assertiveness. Subsequently, the Marines swiftly embarked upon the northern Okinawa offensive, effectively encircling and neutralizing pockets of enemy resistance.[7]

As Tenth Army continued its advance, the Japanese launched repeated concentrated air assaults against Spruance's fleet. Employing a combination of conventional and kamikaze tactics, these attacks inflicted substantial damage and resulted in the sinking of numerous vessels, including an ammunition ship. On 7 April, the Japanese Navy dispatched a task force led by the battleship Yamato, which was intercepted and sunk halfway to Okinawa.

In a letter to his wife Adele dated 14 April, Buckner reported, “We are constantly under air attack but our carrier planes and my own operating from captured fields have done a splendid piece of work and shot down several hundred of the attacking planes.” He further noted, “The quality of Jap pilots is deteriorating and those recently encountered show evidence of hasty and inadequate training.”[8]

In the southern sector of Okinawa, XXIV Corps confronted Ushijima's fortified outposts and encountered the initial defensive line preceding Shuri. The 96th Infantry Division engaged Kakazu Ridge, while the 7th Infantry Division confronted a series of ridges adorned with bunker-like stone tombs. Despite repeated assaults by both divisions, little headway was achieved. Compounding the challenge was the imperative need to conserve ammunition due to the loss of supply ships offshore. By 12 April, after three days of intense combat, the corps had advanced a mere 500 yards, prompting a temporary halt to regroup. Amid fierce fighting, a Japanese counterattack was successfully repelled. Reflecting on the grim reality of the situation, General Hodge remarked, “It is going to be really tough. . . . I see no way to get them out except blast them out yard by yard.”[9]

Buckner maintained a sense of optimism amidst the challenges. In a letter to Adele, he reflected, “In the south, we are up against the most formidable defenses yet encountered in the Pacific, well backed up by artillery and Navy mortars. . . . Since we have all the airfields that we need to work on for the present, I am not hurrying the attack on the south but am greatly reducing casualties by a gradual and systemic destruction of their works. This we are doing successfully and can, I feel confident, break their line in ample time for our purposes.”[10]

Meanwhile, offshore, Bruce's 77th Infantry Division launched an assault on Ie Shima on April 16. Following four days of intense combat, the island fell, securing a vital airfield. Tragically, on 18 April, the third day of the invasion, war correspondent Ernie Pyle lost his life in the fighting. The division later erected a monument at the site where they "lost a buddy," a poignant tribute from the World War II GI.[11]

In the interim, General Hodge marshaled the 27th Infantry Division as reinforcements and recommenced the offensive on 19 April. A combined barrage of land-based artillery and naval gunfire inaugurated the assault, marking the commencement of the largest bombardment witnessed in the Pacific War. Despite the concentrated firepower, the entrenched Japanese forces remained largely impervious, launching a fierce counteroffensive against the advancing Americans. In response, American infantry adopted what Buckner described as "blowtorch and corkscrew" tactics, utilizing explosives and incendiary devices to isolate and eliminate Japanese strongholds.

For five days, Ushijima's defenders fiercely contested Hodge's advances, engaging in relentless back-and-forth combat. However, mounting casualties eventually compelled Ushijima to issue a directive for a strategic withdrawal southward. The attacking divisions, too, suffered substantial losses; a private from the 96th Infantry Division recounted that only 11 out of the 44 men in his platoon emerged unscathed following this phase of the conflict.[12]

The last ten days of April marked a pivotal juncture in the Okinawa campaign. Formal resistance in northern Okinawa ceased on 20 April, just a day before Bruce officially declared Ie Shima secure. These triumphs freed Geiger's corps and Bruce's division for potential redeployment, prompting Buckner to solicit input from his staff and peers regarding the optimal utilization of these troops.

During days of deliberation, various officers advocated for deploying one division to execute a landing at Minatoga and encircle the Japanese stronghold at Shuri. Conversely, others correctly highlighted the exhaustion and depletion of XXIV Corps resulting from recent engagements, stressing the need for reinforcement. Additionally, Buckner faced mounting pressure from Admiral Nimitz to intensify the offensive. On 23 April, Nimitz lamented, “I’m losing a ship and a half a day. So if this line isn’t moving in five days, we’ll get someone up here to move it so we can all get out from under these damn kamikaze attacks.”

Figure 3. Left to right, Spruance, Nimitz, and Buckner. (Source: US Army)

Buckner meticulously assessed all potential courses of action. He recognized the necessity of maintaining available forces for the forthcoming Phases IIIc and IIId, a consideration that tempered his inclination to commit his army excessively to the Okinawa theater while those operations remained pending. Concerns lingered regarding the viability of Minatoga's beaches and terrain for facilitating a swift landing and breakthrough. Additionally, it appeared that Ushijima’s strength was nearly exhausted.

Moreover, Buckner expressed reservations to his staff regarding the feasibility of a Minatoga operation, likening it to “another Anzio, but worse.” This analogy referenced the landing and subsequent siege of the Anzio beachhead in Italy from January to May 1944. Initially anticipated as a swift victory, the operation instead led to protracted and challenging engagements that ensnared Allied forces near Cassino and Rome.

Buckner ultimately directed Geiger's corps and Bruce's division to bolster the front lines opposite Shuri. With their deployment completed, Tenth Army would initiate a fresh series of offensives aimed at capturing Shuri. This decision to forgo a landing at Minatoga, contentious at the time, remains the most disputed aspect of Buckner's handling of the Battle of Okinawa.[13]

The redeployments were finalized by the end of April, and the newly arrived troops promptly launched assaults against Ushijima's defenses. Buckner personally visited both the 77th and 1st Marine Divisions to assess their performance. Reflecting on the experience, he noted in his diary, “It was apparent to me that the 77th Div and the 1st Mardiv entered the line expecting to show their superiority over their predecessors by a rapid breakthrough of the enemy’s position. . . . They were promptly stopped and learned some valuable lessons today. From now on they will be more valuable as all-around fighters.”[14]

The intensity of combat escalated during the initial week of May. Tenth Army found itself contending with a determined Japanese counteroffensive, which was decisively repelled from 4 May to 6 May, resulting in significant losses for Ushijima's forces. On 15 May, Nimitz issued orders to commence Phase IIId, coinciding with the auspicious news of Germany's unconditional surrender. Buckner remarked, “At noon every gun of our land and ship support batteries fired one round at the enemy. We then tuned into the Jap radio frequency and announced in Japanese that the volley was in celebration of the victory. Tomorrow we are dropping an extra of our Jap newspaper with elaboration of this news.”[15]

However, Buckner also lamented the onset of heavy rainfall, which impeded the movement of tanks and slowed the overall advance. This precipitation marked the beginning of a protracted period of torrential downpours, with Okinawa receiving a total of fifteen inches of rain between 7 May and 31 May, with ten inches falling within the final ten days of the month.[16]

On 11 May, Tenth Army launched a comprehensive offensive along its entire front line. In the western sector, the 6th Marine Division captured Sugar Loaf Hill after a week of fierce combat, subsequently securing the city and harbor of Naha. Simultaneously, to the east, the 1st Marine Division penetrated the Wana Draw, posing a direct threat to Shuri itself. Further eastward, the 77th and 96th Infantry Divisions of XXIV Corps made significant territorial gains, facilitating the maneuver of the 7th Infantry Division past the Japanese eastern flank at Yonabaru.

Figure 4. American tanks attack Shuri’s outer defenses. (Source: US Army)

In the waters offshore, kamikaze assaults against the Fifth Fleet escalated throughout May. VADM Marc Mitscher, in command of the carriers of Task Force 58, had to escape when kamikaze planes damaged his flagship. Despite the concerted Japanese air campaign aimed at repelling it, the fleet steadfastly maintained its position offshore, providing unwavering support to Tenth Army. Toward the end of May, command of the fleet shifted to ADM William F. Halsey, succeeding the more cautious Vice Admiral Spruance. While Spruance opted to keep his ships near Okinawa, Halsey directed the carriers to launch strikes against air bases within mainland Japan.[17]

By 21 May, Tenth Army had gained a decisive advantage. The 7th Infantry and 6th Marine Divisions poised themselves for a pincer movement aimed at encircling Ushijima's defenders. However, adverse weather conditions thwarted further progress. “Heavy rain has stopped our tanks,” recorded Buckner, “and is impeding supply just at a time when rapid progress . . . is most desirable.”[18]

Ushijima opted for a strategic withdrawal, leaving behind an outpost line to cover the retreat. Although it took several days for American intelligence to discern the Japanese movement, Buckner promptly sprang into action upon receiving the intelligence. “Initiate without delay,” he ordered, “strong and unrelenting pressure to ascertain probable intentions and keep him off balance.” All units surged forward, confronting determined Japanese resistance. The pivotal stronghold of Shuri was captured on 31 May by the 1st Marine Division. “Ushijima missed the boat on his withdrawal from the Shuri Line,” Buckner informed his staff that day. “It’s all over now but cleaning up pockets of resistance. This doesn’t mean there won’t be stiff fighting.”[19]

In Tokyo, there was a growing realization that the tide of the battle had turned. “Toward the end of May, however, air operations became gradually deadlocked, and IGHQ felt that it was impossible to turn the tide,” recalled Colonel Hayashi. “Command of the skies over Okinawa lay completely in the hands of the U.S. Air Force; the Japanese Navy had already been rendered impotent. Thus the fate of the Thirty-Second Army was just a matter of time.[20]

By this juncture, it became evident to the Americans that Okinawa held significantly more strategic value as a base than previously acknowledged. Recognizing this, Buckner and others proposed to Nimitz that the island be retained as a US protectorate post-war, rendering other potential bases in the Ryukyus unnecessary. Consequently, on 8 June, Nimitz terminated all remaining phases of Operation Iceberg that had yet to be executed and directed Buckner to focus exclusively on concluding the battle on Okinawa.[21]

The remnants of Ushijima's decimated army, now comprising a mere 30,000 men, entrenched themselves along a hill range six miles south of Shuri. Tenth Army probed these fortified positions before launching a concerted offensive on 9 June. Over the course of eight days of relentless combat, the Americans systematically dismantled each Japanese stronghold. Ushijima's positions were subjected to relentless bombardment from artillery and airstrikes, with American tanks providing support for infantry assaults. In certain instances, gasoline was utilized to flush out entrenched defenders from caves and bunkers, which were then set ablaze. Despite Ushijima's orders for counterattacks, each attempt met with resounding failure.[22]

Simultaneously, the 6th Marine Division redirected its efforts towards neutralizing the Japanese naval units safeguarding Oroku peninsula. Employing amphibious and ground assaults, the Marines encircled the 4,000 defenders situated amid the hills at the peninsula's heart. Over the course of ten days, the Marines systematically cleared the hills, gradually eradicating Japanese resistance.[23]

Buckner sensed that victory was within reach. On 10 June, he made an appeal to Ushijima to cease resistance, but received no response. “We have passed the speculative phase of the campaign,” he told his staff on 15 June, “and are down to the final kill.”[24]

Unfortunately, Buckner did not live to witness the ultimate triumph. While visiting the 8th Marine Regiment on 18 June 1945, he fell victim to Japanese artillery fire—the highest-ranking American casualty inflicted by enemy forces in both World War II and the twentieth century. On 19 June, Geiger announced his promotion to lieutenant general and assumed command of Tenth Army, thereby becoming the first (and only) US Marine and aviator of any service to command an American field army.[25]

Undeterred, Tenth Army pressed forward with renewed determination under Geiger's leadership. Meanwhile, US Army Chief of Staff General George Marshall designated GEN Joseph W. Stilwell as the new permanent commander of Tenth Army. On 22 June, Geiger officially declared Okinawa secure and presided over a ceremonial flag raising. The following day, Stilwell arrived on the island and assumed command.[26]

Fighting persisted for another week as Stilwell directed a methodical advance northward. In the waning days of June 1945, Tenth Army inflicted heavy casualties on the Japanese, resulting in 8,975 enemy fatalities and more than  2,900 prisoners captured. Thousands of disoriented civilians emerged from hiding in caves. On 2 July 1945, major combat operations on Okinawa concluded, and Operation Iceberg officially ended. It had been 91 days since Buckner led his forces ashore at Hagushi.[27]

The Battle of Okinawa: Key Lessons

World War II in the Pacific epitomized a conflict where all three services—land, sea, and air—had to synchronize their efforts to secure victory. The success of any single service was contingent upon the cooperation and effectiveness of the others. This principle applied equally to both American and Japanese forces, underscoring the indispensability of joint operations. By various metrics, the Pacific theater stands out as the most integrated theater in which the United States military has ever engaged. Reflecting on the invasion of Okinawa in the context of potential future conflicts over Taiwan or other Pacific islands, three primary lessons emerge.

The Ground Battle Is Paramount

It may appear self-evident, but in a battle aimed at seizing control of an island, the advancement of ground forces dictates the tempo. Regardless of triumphs at sea or in the air, the progress made on land is the linchpin for achieving the objective.

Both Spruance and Turner understood this fundamental truth, having overseen numerous intricate amphibious operations prior to Iceberg. Throughout those campaigns, Spruance consistently orchestrated Fifth Fleet's movements to provide optimal protection to the beachhead and the vulnerable transport and supply vessels. Additionally, he ensured that the forces deployed onshore received ample naval gunfire support. These same priorities guided Spruance during his tenure off the shores of Okinawa.

Turner, for his part, acknowledged the necessity of sustaining and bolstering Buckner's efforts. The amicable rapport and mutual respect shared between the two men fostered a collaborative environment, facilitating smooth interactions between their respective commands. Turner's supportive demeanor was particularly evident during the discussions in late April regarding the potential envelopment landing at Minatoga.

Elwyn Post, Buckner's chief of staff, recounted that “General Buckner wanted very much to make the landings on the southern shore” at Minatoga. He studied the matter thoroughly, discussed it at length with Admiral Turner, and the commanders involved. It was only after he had weighed all factors that he dismissed the plan as being too hazardous . . . Admiral Turner stood ready to back any decision of General Buckner’s which he considered his forces could support. He considered General Buckner’s decision correct and sound.”[28]

At theater headquarters, Admiral Nimitz comprehended the pivotal importance of Tenth Army's success in securing Okinawa. However, Nimitz was also acutely aware of the steep costs involved, particularly during periods when the ground battle appeared to be at a standstill. This awareness is evident in his remarks to Buckner on 23 April regarding the losses sustained by the fleet. Nevertheless, as the campaign unfolded, Nimitz publicly defended Buckner against criticisms of sluggish progress.

Nimitz was not alone among naval officers in supporting the efforts of the ground forces. “Faced with such defensive works as General Ushijima devised,” recalled Samuel E. Morison, an Okinawa veteran, “no army on earth could have done better than General Buckner’s Tenth.”[29]

Projections of a potential battle for Taiwan mirror the dynamics of Iceberg, with a fleet facilitating the landing and sustaining ground operations through an extended deployment. Once deployed, the ships are constrained to the beachhead area with limited operational range until the outcome of the ground battle is determined. If the ground campaign falters or reaches a stalemate, the fleet could remain committed for an extended period. Senior leaders of an invading force would likely encounter similar challenges and dilemmas as those faced during Operation Iceberg. The lessons gleaned from the experiences of Okinawa provide valuable insights for planners and operators to consider and anticipate.

Airpower Decides the Offshore Battle

The offshore battle is primarily for surface dominance, yet its outcome is ultimately determined in the air. This principle was clearly reflected in American tactics off the coast of Okinawa. Spruance's fleet strategically positioned destroyers at advanced radar picket stations to provide early detection of approaching enemy strikes. Each individual ship employed its own antiaircraft fire, damage control measures, and maneuvering techniques for self-defense. While these methods were effective, a crucial aspect of the fleet's defense lay in its airpower, manifested through combat air patrols conducted by carrier-based air groups and fighters stationed in Okinawa by the Army and Marine Corps. Moreover, American aircraft successfully sank the Yamato battleship when it attempted to intervene and launched strikes on Japanese air bases, significantly hampering their ability to launch attacks on the fleet. As the battle progressed, it became increasingly evident that American air superiority was insurmountable, ensuring that the invasion fleet would continue to provide support to the ground battle until its conclusion.

Figure 5. A kamikaze is about to strike USS Missouri off Okinawa. (Source: US Navy)

The significance of air dominance had been underscored in preceding island battles. During the May 1941 conflict off Crete, German airpower engaged the British Royal Navy while German paratroopers confronted Allied ground forces on the island itself. A German historian described the offshore battle as “the first major air-sea conflict in war history,” highlighting how German planes, leveraging air supremacy, relentlessly attacked British ships. “After suffering severe loss the British fleet was compelled to withdraw and the fate of Crete was sealed.”[30]

The Americans encountered a comparable situation just over a year later during the Guadalcanal campaign. Japanese air and surface assaults compelled the invasion fleet to retreat, leaving the 1st Marine Division isolated. Supply and reinforcement proved challenging for the Americans, while the Japanese bolstered their forces and launched offensives. Following several decisive battles in October and November 1942 that tilted air superiority in favor of the United States, the tide turned; the Japanese evacuated the area in early February 1943.[31]

Fighting around Taiwan, encompassing the region of the Taiwan Strait, would likely mirror the patterns observed in the aforementioned cases, involving assaults on surface vessels from both aircraft and missiles, and a contest to establish and maintain air dominance. However, there would be one notable distinction, as none of these historical examples included a significant underwater threat. Conflicts in and around Taiwan are poised to feature a substantial undersea dimension, with offshore fleets contending for supremacy beneath the waves. The developments beneath the ocean's surface may wield comparable influence to the aerial confrontation in shaping the outcome of the invasion.

Local Bases Are Essential

Both Operation Iceberg's adversaries relied heavily on local bases. Okinawa lay within the effective reach of Japanese air and naval resources, both from the home islands and other strategic locations, which the Japanese fully utilized during the operation.

Recognizing the necessity of a nearby base, the United States targeted Kerama Retto as Operation Iceberg's initial objective. Throughout the campaign, this island group served as a crucial American anchorage, providing vital facilities for repair, replenishment, and recuperation. Many damaged vessels underwent basic repairs there before returning to action or sailing to the United States for more extensive overhaul.

On Okinawa itself and its neighboring islands, American air bases hosted a significant air force that supported Tenth Army's ground operations and conducted combat air patrols over the fleet. The abundance of base facilities on Okinawa was such that Buckner proposed to Nimitz that the island become a US possession after the war, a status it retained until 1972. Even after reverting to Japanese administration, Okinawa continues to host several crucial US bases.

In a potential conflict over Taiwan, the proximity of bases will be a critical factor, as basing closer to the theater of operations conserves resources and strengthens operational efficiency. This consideration raises inquiries about the roles of various locations, including the South China Sea islands, the coastal isles of Quemoy and Matsu, and the Pescadores, in any prospective invasion scenario for Taiwan. With modern weaponry, such an operation would necessitate covering a battlespace at least as expansive as that of Operation Iceberg, if not greater. The expanded battlespace would undoubtedly impact US bases in the Ryukyus (including Okinawa), Guam, South Korea, the Philippines, and Japan itself.


Marine MGen Lemuel Shepherd, who commanded the 6th Marine Division on Okinawa and later served as Commandant of the Marine Corps, accurately stated, “The Okinawa Operation was in many ways the most difficult of the Pacific War. Conceived, launched, and supported at long range, it required meticulous detail in both planning and execution. Bad weather, defenses which employed the rugged terrain with great skill and cunning, and a well-trained, resolute defense force combined to give the enemy an advantage that was overcome only by courage, ingenuity, and endurance of the highest order . . . It is a vital chapter in the history of our nation.”[32]

The narrative and insights gleaned from the Battle of Okinawa remain significant. Just as Operation Iceberg offered a glimpse into a potential invasion of Japan itself in 1945, it now provides insights into the dynamics of a prospective invasion of Taiwan nearly eight decades later. The battle holds valuable lessons about integrated sea, air, and land operations where a significant island is the coveted prize and merits comprehensive examination and analysis. ⚔

Christopher L. Kolakowski

Mr. Kolakowski is the director of the Wisconsin Veterans Museum in Madison, Wisconsin. He received his bachelor’s degree in history and mass communications from Emory & Henry College and his master’s degree in public history from the State University of New York at Albany. Kolakowski has worked with the National Park Service, the New York State government, the Rensselaer County Historical Society, the Civil War Preservation Trust, Kentucky State Parks, and the US Army. He is the author of several military history books and articles.  


[1] William Toti, “You Can’t Win Without (More) Submarines,” Proceedings 149, no. 2 (December 2023),; and multiple articles in Proceedings 150, no. 1 (January 2024),

[2] This article is based in part on Christopher L. Kolakowski, ed. Tenth Army Commander: The World War II Diary of Simon Bolivar Buckner, Jr., 1944-45 (Oxford: Casemate 2023).

[3] This profile of Okinawa and plans for Operation Iceberg are from the official histories of the Battle of Okinawa: Roy E. Appleman, et al, Okinawa: The Last Battle (Washington: US Army 1948); and Charles S. Nichols, Jr., and Henry I. Shaw, Jr., Okinawa: Victory in the Pacific (Washington: US Marine Corps 1955). See also the Operation Iceberg Staff Study, available from DTIC,

[4] Ironically, these forces were originally allocated for Operation Causeway, an invasion of Formosa (Taiwan) and the Chinese coast at Amoy. Logistical concerns, plus the decision to liberate the Philippines, dictated Causeway’s shelving.

[5] Saburo Hayashi, Kogun (Quantico: Marine Corps Association 1959), 140–42.

[6] Appleman et al, Okinawa, 74; and Simon Bolivar Buckner diary, 1 April 1945.

[7] Appleman et al, Okinawa, 138–48.

[8] John Toland, The Rising Sun Vol. II (New York: Random House 1970), 845–68; and Simon Bolivar Buckner correspondence, 14 April 1945, Eisenhower Presidential Library.

[9] Appleman et al, Okinawa, 103–37.

[10] Buckner correspondence, 14 April 1945, Eisenhower Presidential Library.

[11] Appleman et al, Okinawa, 149–83.

[12] Appleman et al, Okinawa, 184–248; and Charles Stearns oral history, Wisconsin Veterans Museum.

[13] Appleman et al, Okinawa, 258–64. See also the discussion later in the article.

[14] Buckner diary, 3 May 1945.

[15] Buckner diary, 8 May 1945.

[16] Buckner diary, 8 May 1945.

[17] For details of this and other fleet operations in this period, see Samuel E. Morison, Victory In the Pacific (Boston: Little, Brown 1960), 251–76.

[18] Unless otherwise cited, this section is based on Appleman et al, Okinawa, 360–461.

[19] Appleman et al, Okinawa, 391, 422.

[20] Hayashi, Kogun, 143.

[21] Buckner diary, 23 April and 8 June 1945.

[22] Appleman et al, Okinawa, 422–54.

[23] Appleman et al, Okinawa, 422–54.

[24] Buckner correspondence, 16 June 1945, Eisenhower Presidential Library.

[25] Stephen R. Taaffe, Commanding the Pacific: Marine Corps Generals in World War II (Annapolis: Naval Institute Press 2021), 172; Roger Willock, Unaccustomed to Fear: A Biography of the Late General Roy S. Geiger (Quantico: Marine Corps University Press, 1968),  302. Wallace asserted he should assume command as the senior officer on the island. Geiger, backed by Hodge, cited amphibious doctrine favoring combatant generals in command succession; he also noted Buckner’s preference for Geiger to succeed him. Wallace gave way at that point.

[26] Taaffe, Commanding the Pacific, 172–73; Willock, Unaccustomed to Fear, 302–03. For more on Stilwell’s selection, see Barbara W. Tuchman, Stilwell and the American Experience in China, 1911–45 (New York: Mcmillan,1971), 518–20. Stilwell’s background and activities earlier in World War II are discussed in Kolakowski, Nations In the Balance. The relevant messages are in the MacArthur Memorial Archives, Record Group 4.

[27] Tuchman, Stilwell and the American Experience, 471–74.

[28] Eddie Post, correspondence with John Stevens, 19 June 1946, NARA.

[29] Morison, Victory In the Pacific, 242.

[30] Cajus Bekker, The Luftwaffe War Diaries (New York: Ballantine 1964), 288.

[31] There are many fine histories of the Guadalcanal campaign. One of the most detailed is Richard Frank, Guadalcanal (New York: Penguin 1992). See also Fuji Yu, “An Island Too Far: Lessons From Guadalcanal for EABO” Proceedings 150, no. 3 (March 2024): 46–50,  

[32] Shepherd is quoted in Nichols and Shaw, Okinawa, v.


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