Battle of Okinawa 65 Years Later — May 19, 1945

May 19, 1945

On Okinawa, the US 77th Division suffers heavy casualties while fighting for the Ishimmi ridge and withdraws.

Sherman Flamethrower tank at Okinawa

Okinawa Campaign Background — Col. Unmacht’s Mechanized Flamethrowers

One little known US Army Chemical Warfare Service Colonel stationed in Hawaii made the flame throwing tanks of the Pacific War possible. His ad-hoc team of CWS, Ordnance Department, US Navy See Bees, and private contractors designed and produced both main gun and auxiliary weapon mounted flame throwers for 384 US Army and USMC M3 Stuart light tanks, LVT4 amtracs and M4 Shermans in less than a year.

That compares to a total of five M5A1 “Q” flame thrower tanks and a few dozen M4-5 auxiliary armament flamethrowers the warring Chemical Warfare Service, Ordnance Department and Armored Force bureaucracies managed to get to the Pacific before VJ-Day.

For the Marianas campaign Col. Unmacht’s people converted 24 Marine M3A1 Stuart light tanks into Satan flame thrower tanks and installed six auxiliary hull machine gun mount M4-5 flame thrower prototypes from the USA into USMC M4A2 Shermans.

For the Peleliu campaign Col. Unmacht’s people converted six USMC LVT-4’s into flamethrower vehicles.

For the planned US Army Yap campaign — that turned into the invasion of Leyte — Col. Unmacht’s people converted nine US Army M3A1 Stuart light tanks and an additional LVT-4 into main gun flame throwers.

For Iwo Jima, Col. Unmacht’s people converted eight Marine M4A3 tanks into the what were called in Marine after action reports “CB Mk1” Flamethrower tank using Canadian Ronson flame throwers.

At Okinawa, his team installed 54 Canadian Ronson flame throwers — many from made from airlifted components — into the M4A1 medium tanks of the 713th Flame Thrower Tank battalion.

The other US Army independent tank battalions at Okinawa had eighteen auxiliary periscope flame throwers of CWS-Hawaii manufacture, while each Marine tank battalion carried sixteen built in America bow machine gun E4-5 auxiliary flame throwers. All were installed by Col. Unmacht’s CWS troops.

Both the M4A1 and M4A3 Shermans were called “Flamethrower, Mechanized, POA-CWS “75” -H1 by the Chemical Warfare Service flamethrower group in Hawaii. This stood for “Pacific Ocean Area, Chemical Warfare Service, 75mm gun converted, -H1 model main armament flame thrower.

CWS-Hawaii designed auxiliary periscope flame throwers were designated “Flamethrower, Mechanized, Auxiliary, POA-CWS periscope-H (E4R2) A-H1B” in Army Forces Pacific documents and the US Army World War two “Green book” histories. A total of 176 of these were built.

The more numerous Periscope and machine gun mount auxiliary armament flame throwers were not used to a large extent on Okinawa because they were
1) Shorter ranged 30-40 yards versus 60-80 yards for the 713th’s main armament flame throwers,
2) They carried much less fuel — 25 to 50 gallons depending on the whether one or two pressurized napalm tanks installed — compared to 300 gallons for the 713th’s tanks, and,
3) The auxiliary napalm storage tanks blocked the floor or floor and hatch escape routes in the M4 Sherman.

Several tanks in the 711th Tank battalion had periscope flame throwers ignited by Japanese attacks and had crew burned alive inside their tanks. This compares to no crewmen killed inside a POA-CWS “75” -H1 main armament flame thrower tank in the 713th.

Links consulted for this article:

Chemicals in Combat Chapter 15 (HTML)

Chemicals in Combat (Chemical Corps WW2 Green book)

From Laboratory to Field (Chemical Corps WW2 Green book

Flamethrower Tanks on Okinawa

5 thoughts on “Battle of Okinawa 65 Years Later — May 19, 1945”

  1. They managed to get these weapons assembled and put into the troops’ hands pretty quickly.

    Have our current wars led to a more rapid process of turning ideas into weapons and getting them into the field?

  2. Lex,

    There have been a lot.

    The 1991 Gulf War bunker buster bomb is a classic example.

    The issue for laymen is that the American media only reports military failures under the old “If it bleeds, it leads.”

    There was also political angle during the Bush years that made American media reporting any sort of success in Iraq bad for your media career.

    There have been dozens of successful quick procurement programs in the Iraq war fighting IED’s. I was involved in one of them making armored cabs for FMTV trucks.

    Part of the issue of Iraq was the enemy was listening, so the Military did not advertise the really important sensor/data fusion, intelligence operational analysis and rapid distribution systems we put together to hunt the bomb making gangs there.

    Try google searching using the term “Rapid fielding initiative” for what has been happening lately on the military rocurement font.

  3. Lex,

    You should find this information on the US Army’s Constant Hawk system of interest:

    The Math Matters

    May 20, 2010:

    The best defense against IEDs (aside from alert people in the convoys) are techniques developed four years ago in Iraq. This involves using manned and UAV aerial reconnaissance aircraft, along with pattern analysis and data mining, to find IEDs (roadside bombs), and the people who plant them, before the convoys arrive.

    To do this, the U.S. Army developed an image analysis system that’s basically just another form of pattern analysis. However, it’s been a very successful system when it comes to finding newly planted IEDs. The army named this system, Constant Hawk, one of the top ten inventions of 2006. The army names this top ten each year to give some of the more obscure, yet very valuable, developments some well deserved recognition.

    Pattern analysis is one of the fundamental tools Operations Research (OR) practitioners have been using since World War II (when the newly developed field of OR got its first big workout). Pattern analysis is widely used on Wall Street, by engineers, law enforcement, marketing specialists, and now, the military. Constant Hawk uses a special video camera system to observe a locality and find useful patterns of behavior. Some of the Constant Hawk systems are mounted on light (C-12s, mainly) aircraft, others are mounted on ground structures. Special software compares photos from different times. When changes are noted, they are checked more closely, which has resulted in the early detection of thousands of roadside bombs and terrorist ambushes. This largely eliminated roadside bomb attacks on supply convoys in Iraq, which travelled the same routes all the time. But those routes were also watched by Constant Hawk. No matter what the enemy did, the Hawk noticed. Eventually, the Hawk, and several other efforts, morphed into a campaign that led to the death of over 3,000 terrorists caught in the act of setting up roadside bombs, or lying in wait to set them off and attack their victims with gunfire. Hundreds more terrorists were captured, and many thousands of roadside bombs were avoided or destroyed before they could go off.

    All this geeekery works, and the troops like tools of this sort mainly because the systems retain photos of areas they have patrolled, and allows them to retrieve photos of a particular place on a particular day. Often, the troops returning from, or going out on a patrol, can use the pattern analysis skills we all have, to spot something suspicious, or potentially so.

    A related math tool is predictive analysis. This was widely used in Iraq to determine the identity of bombers were, where they were, and where they were most likely to place their bombs next. This enabled the geeks-with-guns (the Army OR specialists) to offer regular “weather reports” about expected IED activity. The troops took these reports very seriously, especially those who ran the hundreds of daily convoys that moved people and supplies around Iraq. If your route was predicted to be “hot”, you paid extra attention that day, and often spotted IEDs that, as predicted, were there. Usually, the predictions were used to send the combat engineers and EOD (Explosive Ordnance Disposal) teams out to scout and clean the route. It’s the feedback from these guys that has brought the geeks their reputation. If the geeks, and their tools (computers, aerial images, and math), say there is something bad out there, they are generally right. For the geeks, it’s all pretty obvious. Given enough data, you can predict all sorts of things, or just about anything, really. But to many people, including most reporters, it’s all still magic. Task Force Odin is the latest name for an effort that has been going on for over four years, and traces its origins back to World War II, and the invention of Operations Research in the decade before that.

    Afghanistan is different from Iraq, in terms of geography and the psychology of the enemy. But this doesn’t matter. The system still analyzes, interprets, and it tells you what the bad guys are up to and where they are.

  4. Trent, this is good to know.

    I recall seeing this book about counter-mine warfare during the Rhodesian counter-insurgency campaign.

    IEDs turned out to be the biggest threat / challenge in Iraq.

    I wondered at the time whether the U.S. military was even aware that this expertise existed, and if we learned from it? How many wheels were reinvented?

  5. >>How many wheels were reinvented?

    Most anti-mine technology the USA uses in terms of mine protected vehicles is South African in origin.

    The mine campaign of Rhodesia was replicated in South Africa with many of the white losers from Rhodesia passing on what they had learned to the White minority government of South Africa in the 1970’s and 1980’s.

    After the South Africans owned up to building several nukes when the White Minority government folded. Their arms firms (ARMSCOR & DENEL?) were hit by a US nuclear technology fraud related arms embargo.

    This cut the US military off from South African anti-mine technology all through the Bosnia mess of the 1990’s.

    BAE and a few other non-US companies got licences to that South African technology and sold it in small quantities to US firms doing Bosnian anti-mine work in the late 1990’s and then to the DoD directly from 2005 onward when the IED campaign kicked off in Iraq.

    Now the anti-mine/IED technology the US military has deployed is better than anyone elses because it had several years of high intensity mine combat against really good mine emplacers that honed both its tactics and technology.

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