The Battle of Okinawa — 65 Years Ago today, May 16, 1945

May 16, 1945

On Okinawa, the US 6th Marine Division (part of US 3rd Amphibious Corps) reports heavy casualties in continuing attacks on Sugar Loaf Hill.

Japanese antitank guns knock out a number of American tanks supporting an advance, by US 1st Marine Division, along the valley of the Wana River.

Attacks by the US 77th Division to the north of Shuri continue to be unsuccessful.

The US 96th Division reaches the edge of the village of Yonabaru.

Love Hill, to the west of Conical Hill, continues to be held by Japanese forces.

Okinawa Campaign Background — SHINYO! Kamikaze Part Two

The picture of Kamikaze’s off Okinawa is that of burning Japanese planes crashing into carriers and battleships off the coast. While these were the the majority of Kamikaze attacks, they were not the only ones.

IJA Suicide Explosive Motor Boat

The smaller islands of the Ryukyu Island chain that Okinawa was a part of hosted hundreds of explosive motor boats (EMB) of the Japanese Navy’s “Shinyo” (Sea Quake) and Japanese Army’s “Maru-ni” types.

The invasion of the Kerama Retto anchorage several days before Okinawa proper saved the Okinawa invasion flotilla at Hagushi beach the attack of several hundred EMB the night of 1-2 April 1945. These suicide craft were well hidden and had been completely missed by Navy aircraft.

The more numerous, nimble and speedy “Brown Water” PT-boats of the US Navy’s 1942-43 Solomons and 1942-1944 New Guinea Campaigns were left in the Philippines by Admirals Turner and Nimitz. This left overworked fleet destroyers, slower destroyer escorts and very slow converted landing craft gunboats of the Pacific “Blue Water” fleet to face the EMB threat alone.

This was a mistake that would cost hundreds of unnecessary US Navy casualties, as can be seen from the following combat history that is clipped from from

26 March 1945:
Kerama Retto, 15 miles off Okinawa’s southwestern tip. The 77th Infantry “Statue of Liberty” Division lands to capture advance bases and anchorages for the invasion of the main island of Okinawa. The 77th captures and destroys more than 300 IJA “Maru-ni” EMBs that were well dispersed in well camouflaged hideouts. Not one of these EMBs attacked a single American ship.

29 March 1945:
15 EMBs of the 42nd Shinyo Squadron sortie at night, but find no targets. While returning to Yontan in the daytime, they are attacked by USN aircraft and all are sunk.

31 March 1945:
About 50 IJA Maru-ni EMBs based at Bisha Gawa sortie in the moonlight against the American invasion fleet. Most are shot to pieces before they can reach the transports, but one EMB rams USS LSM-12 (Landing Ship Medium) and the explosion tears a huge hole amidships. LSM-12 stays afloat until 4 April when she flounders.

1 April 1945: American Operation “Iceberg” – The Invasion of Okinawa:
At 2100, while screening an LST Group during its night retirement, USS VAMMEN’s (DE-644) bow strikes an object (possibly a depth charge dropped by an EMB) that explodes beneath her stern at 26-18N, 127-29E. The destroyer escort’s starboard propeller is damaged, but she completes her mission.

That same day, Shinyo Squadron 42’s last two EMBs sortie, but both are sunk in Nakagusuku Bay.

3 April 1945:
Rear Admiral Ota Minoru (41)(former XO of YAMASHIRO), CO of the Okinawa Area Auxiliary Base Force, orders all remaining Shinyo to sortie against the American invasion forces.

3/4 April 1945:
Four EMBs of Lt Toyohiro’s 22nd Shinyo Squadron sortie against the Americans. Not far from their base near Chinen, they attack two Landing Craft Infantry-Gunboats. The EMBs attack the gunboats in pairs. The first pair misses their target astern; but an EMB of the second pair rams Lt ( j.g.) Theodore Arnow’s LCI (G)-82 just forward of the bridge killing eight crewmen. Arnow orders Abandon Ship and LCI (G)-82 sinks.

9 April 1945:
In the early morning, destroyer CHARLES J. BADGER (DD-657) lays to at her fire support station at 26-18N, 127-39E. Suddenly, an EMB speeds out of the half light, drops a depth charge close aboard, and races away. The explosion knocks out BADGER’s engines and causes heavy flooding. A tug brings BADGER into the Kerama Retto roadstead. After temporary repairs, she proceeds to Washington state for overhaul.

Off Hagushi. At 0420, while attack cargo ship USS STARR (AKA-67) is loading empty shell casings, the ship is raked by an explosion at 26-20N, 127-44E. EMB No. 325 explodes as it contacts one of a cluster of STARR’s landing craft moored along her starboard side. STARR suffers no damage, but the blast injures four men. The two Japanese aboard EMB No. 325 are KIA.

15 April 1945:
West of Naha. Motor minesweeper YMS-331 is damaged by an EMB at 26-15N, 127-36E.

27 April 1945:
Nakagusuku Wan (Buckner Bay). Destroyer USS HUTCHINS (DD-476), while engaged in close support operations, is attacked by EMBs at 26-14N, 127-49E. A small boat slips through the formation and drops two depth charges close aboard. HUTCHINS is shaken violently by the explosions and her hull is damaged severely, but she suffers no casualties. Damage control parties bring flooding under control. HUTCHINS retires to Kerama Retto for temporary repairs. On 15 July ’45, she arrives at Portland, Oregon for permanent repairs, but she is scrapped after war’s end.

28 April 1945:
An EMB damages cargo ship BOZEMAN VICTORY (VC2-S-AP3). The explosion injures six men among the 59-man merchant crew. 13 stevedores and men in the “Victory” ship’s Armed Guard also suffer injuries.

4 May 1945:
Nagagusuku Bay. Coast Guard-manned PC-469 is on anti-sub patrol in the area. At 0035, three small craft are sighted at about 1,000 yards. PC-469 challenges the boats, but it is not answered. The boats are identified as Japanese EMBs. PC-469 opens fire. One EMB is sunk about 40 yards astern. PC-469 observes an explosion and an underwater concussion is felt throughout the sub-chaser. The two remaining boats clear out to about 600 yards. At 0050, TG 51.19’s destroyers illuminate the EMBs. PC-469 sinks another suicide boat about 75 yards off the starboard quarter.

North end of Nakagusuku Wan. That same day, an EMB rams cargo ship USS CARINA (AK-74) port side at 26-13N, 127-50E. The explosion buckles deck plates, tears a hole in the transport’s side, knocks out a boiler and causes flooding of a hold. Six of CARINA’s crewmen are injured. Skillful damage control saves CARINA and her cargo. She completes unloading, then heads for repairs at Ulithi.

15 May 1945:
All IJN and IJA EMBs are eliminated as operational combat units. Their crews continue fighting as infantry near Naha.

14 June 2010 Update:

This is a clip from the hyperwar site that I meant to place in this post when it was first published.

The Amphibians Came to Conquer

“Planning for Use of PT Boats at Okinawa
Before relating the story of the Okinawa assault, the reason for the absence of PT boats in the assault forces will be mentioned.
Vice Admiral Turner, and many other naval officers who had witnessed the PT boat operations in the Guadalcanal and New Georgia operations, thought that the PT boats were anywhere from somewhat to vastly overrated by the public and the press.
Admiral Hall tells the story that prior to the Okinawa operation the overall commander of the PT boats, who had participated in the South Pacific operations, reported to him in Leyte for duty in connection with training for the upcoming Okinawa landings. Admiral Hall asked Admiral Turner by despatch what part the PT boats would play in the operations so he could arrange appropriate training for them. Vice Admiral Turner informed Admiral Hall that the PT boats would not even be allowed to enter the Okinawa area until D plus 4 or later. Admiral Hall explained:
He evidently had no use for them, and I had no use for them. When I was doing my part of the Normandy landing, (OMAHA Beach) they were of no use whatsoever.32”