Thread by @TrentTelenko

Two days ago plus a further 76 years (27 Apr 1945) the capstone logistical catastrophe of the Okinawa Campaign occurred.

The US Army ammo ship SS Canada Victory was given a berth far from the shipping off Hagushi beach by the SOPA. She was struck & ignited. The 7,400 tons
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...of artillery ammunition aboard her burned.

Nor was she the only Army ammo ship damaged off Hagushi Beach 27 Apr 1945.

The SS Clarksdale Victory was also struck by Japanese artillery & the SS Bozeman Victory took rudder and propeller damage from a ram from another ship...
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...maneuvering during the 27 Apr 1945 air attacks.

This is how page 36 of "Contribution to Victory - The Distribution and Supply of Ammunition and Ordnance in the Pacific Theater of Operations" describes the impact to the Battle of Okinawa.

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That 21,000 tons of ammo lost to sinking's number comes from the 2nd volume of the Tenth Army AAR here:

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The 21,000 ton number was very much soft peddled in the US Army Green book THE LAST BATTLE to make out -- by shell numbers -- that the horrendous damage done to 10th Army firepower at Okinawa...wasn't.

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Bar charts like that are why people say things like: "There are lies...

There are dirty lies...

And then there are statistics.

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Speaking of lying with statistics, attached is the 1st page of encl. 3 in the 10th Army Ordinance staff section. It lists ships, their ammo tonnage, where loaded, arrival date plus their beginning and ending unloading dates.

At 7,400 ton per sunken ship, there were 22,200...
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...tons of artillery ammo lost, not 21,000.

Nothing like "Rounding Errors" that magically disappear 1,200 tons of Army artillery ammo that got blow up because the US Navy Senior Officer Present Afloat refused to protect the ships carrying them.

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I've already had a thread on that here for more details on USN SOPA doctrine in WW2.

https://twitter.com/TrentTelenko/status/1379938884654620672

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This thread is a deep dive on what this 'capstone logistical catastrophe' in the 10th Army artillery did to the ground campaign on Okinawa & it's impact on Operation Iceberg Phase III operations.
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I've spoken in the other thread on how the loss of mortar and VT-fused ammo robbed 10th Army of the ability to engage the defilade dead space on the back of hill masses at Okinawa.

Photo source: FM 7-90, Ch7, Fig7-3 Artillery Dead Zones
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There was another very deadly detail in this wanton destruction of artillery ammunition...the data cards.

The 1996 version is shown attached.
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Ammunition data cards have fine details of manufacture that are essential for accurate placement of shellfire & screening out bad Mfg lots.

Photo clip from DODIG-2016-084
media.defense.gov/2016/Apr/29/20…
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The destruction of the three US Army Victory class ammo ships forced 10th Army to spread III Marine Amphibious Corps artillery & AA ammo across dozens of US Army artillery & anti-aircraft battalions in Mid-Apr 1945.

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The mixed ammo lots issued to some units were causing issues for ballistic computation.

One US Army 90mm AA gun battalion was firing ammunition from three different lots!

These AA gun battalions were the lucky ones.

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April 1945 was before the age of electrostatic copying. Ammo cards of that era were a typical triple copy carbon paper.

Mimeograph machines were heavy, required special chemicals plus paper to copy with...and 10th Army didn't plan print more cards.
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Tenth Army staff thought it brought more than enough ammo not to need to spread lots between gun battalions.

This meant that the initial infantry assaults on the Shuri line starting 9 Apr 1945 not only lacked dead space preparation. The artillery ammo on hand simply
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... could not be risked danger close.

And those were just the tactical effects on Okinawa ground operations.

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The operational effects were much larger.

Operation Iceberg was planned in three phases. Phase 1 - the taking of southern Okinawa - was to be 30 days.

Phase II - the taking of Ie Shima & Northern Okinawa - was to take another 30 days with only 40 days of heavy
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...artillery combat between them.

Taking Southern Okinawa took 82 days versus the 30 planned, and the US Navy lost 22,200 tons of artillery ammo intended to fight it.

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Okinawa occurred in the middle of a world wide US Army shell shortage. Worse, it was after General MacArthur's assault on Spanish Intramuros fortress in Manila.
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There simply was no more US artillery ammunition anywhere for General Buckner to draw upon until after the Germans surrendered...and it would take 45 to 90 days from a US port of embarkation to Okinawa.
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General Buckner's logistical "bill payers" to complete Okinawa phase I were all the Phase III Operations.

In Feb 1945 Phase III A (OKINO DAITO JIMA. THREADWORM) and Phase III B (KUME SHIMA/KNOWLEDGE) had been cancelled to concentrate on Okinawa Phases I & II.
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Iceberg Phase III C (MIYAKO JIMA/ADJUTANT) was a 3 division assault by III Marine Amphibious Corps planned for 1 June 1945 and was to build 2 Ftr Strip & 1 HB Strip.

It's cancellation on 27 Apr 1945 freed up 21,200 tons of artillery for Okinawa Phase I.

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That this was almost exactly replaced the 22,200 tons of artillery ammo lost in the burning hulks of the SS Hobbs Victory, SS Las Vegas Victory & SS Canada Victory the day the last of them sank was just a..."happy accident."

And Joe Izuzu has a truck to sell you.
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The next two Phase III operations cancelled were Phase III E (Tokuno/ADJOURN) and then Phase III D (KIKAI SHIMA/FRICTION).

Both were reinforced division sized assaults and neither had the ammo tonnage payoff that MIYAKO JIMA/ADJUTANT did.
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Essentially the German surrender on May 7, 1945 allowed Adm Nimitz to commit all of his Marianas theater artillery stock to complete Okinawa. Since his theater was now America's top priority for replacement artillery ammunition.
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The price of these Phase III invasion cancellations can be seen in Olympic May 1945 and June 1945 air coverage maps.

This map shows convoy air cover from KIKAI SHIMA/ FRICTION vs Okinawa (green lines).

The former covered Kyushu beaches and Okinawa did not.
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This Operation Olympic planning map is from June 1945 & shows completely changed planning assumptions. Land based airpower will no longer provide air superiority coverage.

These ranges reflect long range strikes against fixed targets vs Japanese strike ranges.

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The US Navy had signed up for providing air superiority over Kyushu beaches for 10 days in Operation Olympic until land based air could arrive in force.

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The massive Japanese troop build up on Kyushu in the final days before Japanese surrender was such that General MacArthur pronounced that it would take 20 days, not 10, before land based air would arrive in force.
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Whether it was 10-days or 20-days.

But for the miracle of the A-Bomb, the price of CentPac's failure to protect General Buckner's artillery in April 1945 was placing the entirety of the US Pacific fleet into a Kamikaze kill jar.
/End.

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