Operation Iceberg


It was 65 years ago today . . .

Battle of Okinawa: Operation Iceberg

When two United States Marine and two Army divisions landed abreast on Okinawa on Easter Sunday, April 1, 1945, they faced an estimated 155,000 Japanese ground, air and naval troops holding an immense island on which an estimated 500,000 civilians lived in cities, towns and villages. Operation Iceberg was to be, in every way, vast when compared to any other operation undertaken by Allied forces in the Pacific War under U.S. Navy command. Indeed, using mainly divisions that had already undertaken island-hopping operations in the South and Central Pacific since mid-1942, the U.S. Pacific Fleet stood up the Tenth U.S. Army under Lieutenant General Simon Bolivar Buckner Jr., consisting of III Amphibious Corps and XXIV Army Corps — the largest land command ever assembled under the Navy’s direct control.

To those Japanese who thought the war was winnable, Okinawa was the last chance. The island lay within 350 miles — easy flight distance — from the Japanese homeland and was, by American design, to be the base from which the southernmost Home Island, Kyushu, would be pummeled to dust ahead of the expected follow-on invasion. Anything short of complete victory over Allied air, naval and ground forces spelled doom for Japan — and no such victory was remotely in the cards. Thus, from the Japanese view Okinawa was and could be no more than a delaying battle of attrition on a grand scale. The few Japanese who knew that their country’s war effort was in extremis were content to fight on Okinawa simply for reasons of honor, for all military logic pointed to the same dismal conclusion: Japan was vanquished in all but name as soon as the first Boeing B-29s left the ground in the Marianas, as soon as American carrier aircraft hit targets in Japan at will, as soon as even twin-engine bombers could strike Japanese ports from Iwo Jima, as soon as Japan dared not move a warship or cargo vessel from a port in any part of the shrinking empire for fear it would be sunk by an Allied submarine. By April 1, 1945, all those events were taking place routinely.

Although the Japanese commanders counted 155,000 defenders, of whom 100,000 were soldiers of Lt. Gen. Mitsuru Ushijima’s Thirty-second Army, the rest were of widely mixed abilities, and there were not nearly enough troops to cover the ground the way 23,000 troops had covered Iwo Jima. Therefore the forces on Okinawa were concentrated in a number of sectors that offered the best prospects for a robust, attritional defense. The northern half of the island was virtually conceded, and the south was turned into four extremely tough hedgehog defense sectors. The proportion of artillery and mortars to infantry was the highest encountered in the Pacific War.

Coming to put their defense arrangement to the test was the Tenth Army. The new 6th Marine Division (1st Provisional Marine Brigade plus the 29th Marines and attachments) would land over the northernmost beaches on the western side of Okinawa a little south of the island’s midpoint. It was to strike across the island, then turn north to pacify a little more than half of Okinawa on its own. To the right, the 1st Marine Division was also to strike across the island, then become part of the Tenth Army reserve. The Army’s 7th and 96th Infantry divisions were to land side by side in the southern half of the Tenth Army beachhead and pivot south to cover the width of the island. Also on April 1, the III Amphibious Corps’ (IIIAC) reserve, the 2nd Marine Division, made a feint toward a set of beaches in southeastern Okinawa. This feint was in line with where the Japanese predicted the main landing would take place, so for once a feint actually held large numbers of defenders in place looking the wrong way. Other units, including the Fleet Marine Force’s Pacific Reconnaissance Battalion, were assigned objectives elsewhere in the Ryukyu Islands, most of which were taken or at least assaulted before what was dubbed L-day on Okinawa.

Immediate objectives were Yontan and Kadena airfields, in the IIIAC and XXIV Corps zones, respectively. As soon as these airfields could be brought to operational status, combat-support aircraft would operate from them. Also, many aircraft carriers would remain on station off Okinawa for as long as their air groups were needed. The land-based component was a Marine command named the Tactical Air Force and consisting of several Marine air groups of fighters and light bombers. Marine fighter squadrons based aboard fleet carriers and several new Marine carrier air groups (fighters and torpedo bombers) based aboard escort carriers would be available throughout the land operation.

The landings were made against zero opposition and with almost no casualties. Far from going into a state of optimism, however, the many veterans in the assault force realized that a very hard road lay before them, that the Japanese had chosen to dig deep and fight on their own terms.

Yontan Airfield fell by midmorning, after Marines overcame very light opposition along the juncture of the 1st and 6th Marine divisions. Reinforcements moved to fill gaps that developed due to rapid advances by the 4th, 7th and 22nd Marines. Marines of the 1st Division captured an intact bridge across a stream at the IIIAC-XXIV Corps boundary and overcame hastily built field fortifications all across the division front. Divisional and IIIAC artillery battalions landed routinely, and many batteries were providing fire by 1530 hours. The IIIAC advance halted between 1600 and 1700 to avoid more gaps and to help the Marines on the far right maintain contact with the 7th Infantry Division, whose left flank outpaced the 1st Marine Division right-flank unit by several hundred yards. The halt also gave artillery units outpaced by the rapid advance time to move forward and register night defensive fires.

Basically, all of L-day’s headaches arose from the light-to-nonexistent defensive effort, and not the usual spate of battle problems. Both airfields, Kadena and Yontan, were firmly in American hands by nightfall, and engineers were already at work to get them operational in the shortest possible time.

See also:
Chapter I: Operation Iceberg
Operation Iceberg: The Assault on Okinawa – The Last Battle of World War II (Part 1) April – June 1945
Operation Iceberg: The Assault on Okinawa – The Last Battle of World War II (Part 2) April – June 1945
Battle of Okinawa
Operation Iceberg – Okinawa Invasion
Operation Iceberg: The Battle of Okinawa

Although the initial landings were practically unopposed, the fight for Okinawa quickly deteriorated into a nightmare.

The Battle of Okinawa, which began on Easter Sunday, April 1, 1945, and lasted for three months, was a descent into hell. At no place, at no time, was combat worse than on Okinawa – not at Gettysburg, not in the trenches in World War I, not on the Eastern Front in World War II, not on Iwo Jima. Losses were dreadful: 12,520 U.S. dead, 36,631 wounded; 110,071 Japanese soldiers killed, 7,401 captured (almost all badly wounded); and 140,000 Okinawan civilians dead.

As horrific as the Battle of Okinawa was, Operation Downfall, the invasion of the Japanese mainland, would have been far worse by many orders of magnitude.

/so, don’t let anyone tell you that the U.S. dropping of the two atomic bombs didn’t save lives, on both sides

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