Map Description

History Map of WWII: Okinawa April-June 1945

Illustrating:

Operation ICEBERG

Operation Iceberg was the codename for the Allied invasion of Okinawa.

The Battle of Okinawa was fought from 1 April 1945, when American forces landed on Okinawa, to 22 June 1945, when organized Japanese resistance officially ended. However, clearance operations continued until 30 June.

See this map for the first week (1-8 April) of this operation.

It follows a summary / map of all battle operations from 9 April - 30 June 1945.

Map ⓐ

Southern Okinawa, Naha-Shuri-Yonabaru

XXIV Corps Operations

9 April - 6 May 1945

During the Battle of Okinawa, the XXIV Corps, part of the U.S. Tenth Army, was tasked with assaulting the southern sector of Okinawa, focusing on the Naha-Shuri-Yonabaru line. This area was the heart of Japanese defenses, anchored by a network of fortified positions, natural ridges, and urban strongpoints.

By early April 1945, U.S. forces had landed on Okinawa and quickly moved to isolate the southern part of the island, where the bulk of Japanese forces were entrenched in the Shuri defensive line, a formidable system stretching from Naha (west) through Shuri (center) to Yonabaru (east).

From 9 April, XXIV Corps launched repeated frontal attacks against well-prepared Japanese positions. The terrain favored the defenders: steep ridges, caves, and urban ruins allowed the Japanese to inflict heavy casualties and mount effective counterattacks.

The Americans responded with combined arms tactics — coordinating infantry, armor, artillery, and close air support — to reduce strongpoints and gradually advance.



Key Engagements:

Naha: The port city on the west coast, though initially bypassed during the early phase of the campaign, became a focal point after late May as U.S. forces sought to envelop the remnants of the Shuri Line. It was subjected to heavy bombardment prior to ground assaults. Japanese defenses in and around the city, including fortified buildings, rubble-filled streets, and mined approaches, slowed American progress. Resistance was determined and skillfully conducted, exploiting the urban terrain to maximum effect.

Shuri: The central hub of the Japanese defense, centered on Shuri Castle, was the anchor of the line. Assaults here encountered the stiffest resistance, with Japanese troops utilizing interconnected caves and bunkers.

Yonabaru: On the east, operations aimed to outflank the Shuri line and cut off Japanese retreat or reinforcement routes.

The fighting was characterized by attrition. The Americans steadily wore down Japanese positions with superior firepower, but at high cost. Both sides suffered heavy casualties, and the pace of advance was measured in yards per day.



By early May, XXIV Corps had made significant but costly gains along the Naha-Shuri-Yonabaru axis. However, progress was still grinding and indecisive, especially due to Japanese counterattacks (notably the May 4 counteroffensive, which failed).

The Japanese were forced to withdraw from the Shuri line around 22–23 May, setting the stage for the final phase of the battle and the collapse of organized resistance in southern Okinawa.

Map ⓑ

Southern Okinawa, Naha-Shuri-Yonabaru

Tenth Army Operations

10 May - 30 June 1945

Between 10 May and 30 June 1945, the US Tenth Army conducted the climactic phase of the Battle of Okinawa, the most intense and costly fighting of Operation Iceberg, as American forces aimed to break through the heart of Japanese defenses anchored around the historic Shuri Castle and the fortified ridges of southern Okinawa.

Operations were characterized by methodical, attritional warfare against deeply entrenched Japanese defenders. The capture of the Naha-Shuri-Yonabaru line broke the backbone of Japanese resistance, but at a staggering human cost.

In more detail:

The Tenth Army, under Lt. Gen. Simon Bolivar Buckner, Jr., was a unique joint force comprising four US Army divisions (7th, 27th, 77th, 96th) and three Marine divisions (1st, 2nd**, 6th), with its own Tactical Air Force and support from the US Navy.

** Note: The 2nd Marine Division served as a floating reserve and was never deployed ashore.

The Japanese Thirty-Second Army, led by Lt. Gen. Mitsuru Ushijima, had entrenched approximately 100,000 troops — including regulars, naval infantry, and conscripted Okinawans — into a complex defense-in-depth system across the southern third of the island.



Key Phases and Battles

May Offensive: On 11 May, the Tenth Army launched a coordinated offensive along the entire front. The Japanese had constructed formidable defensive positions — interconnected caves, pillboxes, and tunnels — centered on the Shuri Line, which stretched from Naha on the west, through Shuri Castle, to Yonabaru on the east.

Shuri Castle Assault: The focal point of Japanese resistance, Shuri Castle, was heavily fortified and supported by a series of ridges (notably Kakazu, Dakeshi, and Sugar Loaf). American forces faced fierce resistance, complicated by heavy rains and rugged terrain. After weeks of attritional combat, relentless artillery barrages, and close-quarters fighting, US troops finally captured Shuri Castle on 29 May 1945.

Naha and Yonabaru: Following the fall of Shuri, the US 6th Marine Division advanced westward and engaged in intense urban combat to seize Naha, the island’s largest city, by early June. On 4 June, elements of the division also conducted an amphibious landing on the Oroku Peninsula to outflank entrenched Japanese naval units. Simultaneously, US Army divisions pressed eastward toward Yonabaru, steadily reducing remaining Japanese positions through coordinated envelopment and sustained assaults.

Final Push: The Japanese, recognizing the untenability of their positions, conducted a fighting withdrawal toward the southernmost tip of Okinawa. The Tenth Army maintained pressure, systematically clearing resistance until organized Japanese defense collapsed by 22 June 1945.



Casualties and Significance

The campaign was among the bloodiest in the Pacific, with approximately 160,000 total casualties: at least 50,000 Allied and between 84,000–117,000 Japanese, including many Okinawan conscripts and civilians.

The Tenth Army alone suffered over 7,600 killed and 31,800 wounded, with an additional 26,000 non-battle casualties.

The ferocity of combat, extensive use of kamikaze attacks, and high civilian losses led to the Battle of Okinawa being called by the people of Okinawa the “typhoon of steel” (鉄の暴風).

The fall of southern Okinawa provided the Allies with a crucial staging area for the planned invasion of mainland Japan, though the war would end before that operation commenced.

Credits

Courtesy of the United States Military Academy Department of History.

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