Japan

Battle of Okinawa 65 Years Later — 15 June 1945

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15 June 1945

On Okinawa, Marines suffer heavy casualties and are unable to advance on Kunishi Ridge. The US 1st Division, already short of troops, is attached to the US 2nd Marine Division.

Forces of the US 24th Corps continue operations to eliminate Japanese positions on Mount Yaeju and Mount Yuza.

Landing Vehicle Tracked (LVT) on 01 April 1945

Landing Vehicle Tracked (LVT) on 01 April 1945


Okinawa Campaign Background –– LVT Attrition

The USMC, at the beginning of the Okinawa campaign, had used previous island assaults as the base line for provisioning spares and supports for it’s landing vehicle tracked (LVT).

It was utterly inadequate in the face of the reality of protracted combat on Okinawa:


At the beginning of the campaign, the 4th and 9th Amphibian Tractor Battalions with a total of 205 LVTs were attached to the 6th Marine Division. Added to those in the 1st and 8th Battalions attached to the 1st Marine Division, the total number of LVTs available to IIIAC was 421. IIIAC AR, chap VII, p. 101. The resupply of spare parts for LVTs was totally inadequate, especially in the case of such vitally needed basic items as tracks, track suspension system parts, front drive assemblies, and transmission parts. The lack of all of these deadlined a good many LVTs and severely limited the amount of support they could have provided during the drive to the south and in the Oroku landing. At the end of the campaign, 75 LVTs had been completely destroyed as a result of enemy action, or, having been badly damaged, they were cannibalized for spare parts. Of the 346 vehicles remaining, 200 were deadlined for lack of spare parts. Ibid., p. 102.

There were 421 LVT-3 and LVT-4 on 1 April 1945. By the end of the campaign only 146 of that 421 were operational. A number a hair under 35% of the original starting force.

The logistical implications of those numbers for Operation Olympic in November/December 1945 were daunting.

Battle of Okinawa 65 Years Later — 12 thru 14 June 1945

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12 June 1945

On Okinawa, many of the Japanese naval infantry cut off in the Oruku peninsula, reduced to a pocket of about 1000 square yards, begin to commit mass suicide to avoid surrender.

The US 1st Marine Division captures the west end of Kunishi Ridge during a night attack.

The US 96th Division attacks Japanese positions around Mount Yuza and Mount Yaeju.

13 June 1945

On Okinawa, the Japanese resistance in the Oruku peninsula ends. The US 6th Marine Division records a record 169 Japanese prisoners as well as finding about 200 dead. (This is a large total when compared with previous numbers of Japanese prisoners reported.)

The fighting continues to the southeast, especially in the Kunishi Ridge area where a regiment of the US 1st Marine Division suffers heavy casualties.

The US 24th Corps uses armored flamethrowers in the elimination of the Japanese held fortified caves on Mount Yuza and Mount Yaeju and on Hills 153 and 115.

Battle line on the Kiyan Peninsula, 10-19 June 1945

Battle line on the Kiyan Peninsula, 10-19 June 1945

14 June 1945

On Okinawa, mopping up operations proceed on the Oroku peninsula.

The troops of the US 3rd Amphibious Corps and the US 24th Corps continue to eliminate fortified caves held by Japanese forces on Kunishi Ridge and on Mount Yuza and Mount Yaegu.

An American regiment of the US 96th Division reaches the summit of Mount Yaegu, while the US 7th Division extends its control of Hills 153 and 115.

Okinawa Campaign Background — Goodbye General Mud

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Battle of Okinawa 65 Years Later — 08 thru 11 June 1945

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08 June 1945

On Okinawa, in the north heavy fighting continues on the Oroku peninsula.

In the south, the US 24th Corps prepares to attack Mount Yaeju.


09 June 1945

On Okinawa, the Japanese forces defending the Oroku peninsula are cut off and surrounded by forces of the US 6th Marine Division.

The US 1st Marine Division advance southward to Kunishi Ridge, one of the last Japanese strong points.

10 June 1945

On Okinawa, fighting continues on the Oroku Peninsula, where the forces of the US 6th Marine Division have reduced the Japanese pocket to about 2000 square yards. Heavy Japanese losses are recorded in nighttime counterattacks.

Meanwhile, on the south of the island, the US 1st Marine Division suffers heavy losses in the successful capture of a hill west of the town of Yuza.

The US 24th Corps forces, to the left, launches a major offensive against the last Japanese defensive line, the Yaeju-Dake Line. Japanese resistance is evidently weakening.

YAEJU-DAKE was brought under American artillery fire

YAEJU-DAKE was brought under American artillery fire shortly before the infantry attempted its first advance to the escarpment. Burst at upper left is white phosphorus.

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Battle of Okinawa 65 Years Later — 07 June 1945

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07 June 1945

On Okinawa, in the Oroku peninsula, Japanese forces hold attacks by the US 6th Marine Division while the US 1st Marine Division advances southward and isolates the peninsula defenders.

The US 24th Corps is engaged in artillery bombardments.

Okinawa Background — Colonel Unmacht’s 4.2 inch Mortar Gunboats

A LCI(M) Off Okinawa photographed from the battleship USS West Virginia

LVT amphibious tractors move past LCI(M)-809 (center), bound for the Okinawa landing beaches, 1 April 1945.

The redoubtable Colonel Unmacht of Hawaiian flame throwing tank fame was also responsible for another major innovation in off-shore fire support in WW2 — the 4.2 inch Mortar Gunboat.

They were simply LCVP, LSM and LCI landing craft given one to four 4.2 inch (107mm) mortars to provide fire support for landings. The inability of naval gunfire to hit reverse slopes and the short 1,200 yard range of naval 4.5 inch and 5 inch rockets means that the 3,500-4,500 yard range 4.2 inch mortar was ideal to hit the backs of hills and mountains fronting landing beaches.

This is the time line of 4.2 inch gunboat development which supported not only the Central Pacific, but also General Mac Arthur’s SWPA command and the invasion of Sicily!

1942 – Developing doctrine and experimenting
July 1943 – Sicily
Spring 1944 – Saipan, Marianas Group – aborted operation
21 June 1944 – Bougainville, first successful amphibious combat operation
August 1944 – Training in Empress Augusta Bay, Bougainville, Solomon Islands
15 September 1944 – Peleliu, Palau Islands: first LCI(M) combat use
20 October 1944 – Leyte, Philippine Islands
9 January 1945 – Luzon, Philippine Islands
19 February 1945 – Iwo Jima, Bonin Islands, northwest Pacific basin
1 April 1945 – Okinawa, the Ryukyus Islands, northwest Pacific basin

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Battle of Okinawa 65 Years Later — 05 thru 06 June 1945

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05 June 1945

On Okinawa, Japanese forces on the Oroku peninsula strongly resist the US 6th Marine Division which nonetheless captures most of the airfield.

In the south the forces of the US 24th Corps near the last Japanese defensive line, running from Yuza in the west to Guschichan on the east coast and based on the three hills, Yaeju, Yuza and Mezado.

Oroku and Yaeju-Dake, 4-11 June 1945

Oroku and Yaeju-Dake, 4-11 June 1945

At sea, a sudden typhoon damages 4 battleships, 8 aircraft carriers, 7 cruisers, 14 destroyers, 2 tankers, and and ammunition transport ship, of the US 3rd Fleet.

Two Japanese Kamikaze attacks cripples both the WW1 era battleship USS Mississippi and the heavy cruiser USS Louisville.

06 June 1945

On Okinawa, elements of the US 6th Marine Division advance in the Oruka Peninsula following their landing. Naha airfield is secured.

Elements of the US 96th Division (US 24th Corps) reach the lower slopes of Mount Yaeju and are halted by intensive Japanese fire.

Okinawa Background — The T-6 Ritchie Device

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