Did later campaign assessments conclude Tarawa should have been isolated and bypassed?

[Carl Schwamberger]

Will try to find my book “Utmost Savagery: The Three Days of Tarawa” by Col. Alexander, but IIRC he stated on a TV interview that they counted the latrines and came up to pretty good estimate of the size of the garrison.

Counting latrines was a common technique. I recall it used WWI to estimate the capacity of the German reserve camps on the western front.

[Felix C]

Is there a formula for how many men per latrine seat or stall?

[Carl Schwamberger]

There were several. Experience caused the potty estimate methodology to be refined. The same photographs that reveal outhouses reveal a portion of the weapons emplacements. Those are better concealed than the bath houses, but analyzing those gives you a sense of the number and size of the weapons crews and a guide to likely numbers of infantry and support personnel.

Picking back through Alexanders 'Utmost Savagery' I was reminded the Japanese main fleet sortied from Truk 4-5 weeks earlier looking for a US invasion fleet. Triggered by signals intel, the fleet probed north with air searches east of Wake. Three carriers & six BB along with escorts burned away a uncomfortable amount of fuel. Admiral Koga then decided US activity in the central Pacific a ruse & released additional reinforcements for the ongoing battles surround Rabual & other points in S Pac. On Kogas desk there was a extensive plan for counter attacking any actual central Pacific thrust. As it was Kogas air and light naval forces were badly discombobulated when the intel division started warning of a US attack in the Gilberts on or after 17 November. Kogas earlier decision made a timely reaction to this news problematic.

Another bit of trivia is the log seawall surrounding the tide line of the island was new construction. A few months earlier logs had been cut from the adjacent islands to rebuild the seawall. This benefitted the attackers as it created a near continuous line of cover at the waters edge. While it did block the US M3 & M4 tanks and restrict them to a few gaps for existing the water the rifle squads and other found it invaluable cover. A look at the fields of fire of the Japanese MG bunkers suggest few to none were positioned to enfilade this dead ground with MG fire or other weapons.

[LineDoggie]

So, how many planes were put on Betio Island.

Im guessing that would be in the records of the 7th Air Force. They were operating B24s in the Central Pacific in 1943-44.

I see PBY Catalinas, PV-2 Harpoons, R4D(C-47's) and at least 1 B-24 fuselage @ Hawkins field

https://upload.wikimedia.org/wikipedia/ ... h_1944.jpg


7th AF mentions B-24's, B-25's based or staging out of Tarawa

Makin had A-24's (SBD's) and P-39's, P-40's

https://marshall.csu.edu.au/Marshalls/h ... ology.html

[Delta Tank]

Hindsight is always 20/20...

They knew or had a pretty good idea how large the garrison was. Why attack where you know where the enemy is, when you can seize/occupy islands where the enemy is not? Example Abemama, seized by a company (-) with very few casualties.

And then we repeated this mistake at Peleliu.

Mike

And the garrison was underestimated by approximately half.

Abemama was fine for the large bombers. However, you could not further cram the medium bombers and fighters onto the same airfield.

From the book entitled “Aleutians, Gilbert’s and Marshalls June 1942-April 1944” by Samuel Eliot Morison, printed in 1951, page 149: “Betio had been so thoroughly reconnoitered by aircraft and submarine that the Japanese defenses were well known in advance to the officers entrusted with its capture. Even the number of defenders had been estimated correctly, to within a hundred men.” Footnote #5 will not type it in but it discusses the latrine method of 64 men per hole.

So, we DID NOT underestimate by approximately half.

Mike

[Takao]

Hindsight is always 20/20...

They knew or had a pretty good idea how large the garrison was. Why attack where you know where the enemy is, when you can seize/occupy islands where the enemy is not? Example Abemama, seized by a company (-) with very few casualties.

And then we repeated this mistake at Peleliu.

Mike

And the garrison was underestimated by approximately half.

Abemama was fine for the large bombers. However, you could not further cram the medium bombers and fighters onto the same airfield.

From the book entitled “Aleutians, Gilbert’s and Marshalls June 1942-April 1944” by Samuel Eliot Morison, printed in 1951, page 149: “Betio had been so thoroughly reconnoitered by aircraft and submarine that the Japanese defenses were well known in advance to the officers entrusted with its capture. Even the number of defenders had been estimated correctly, to within a hundred men.” Footnote #5 will not type it in but it discusses the latrine method of 64 men per hole.

So, we DID NOT underestimate by approximately half.

Mike

Ummm...Estimates ran from 2,600-3,200. When there were 4,600 on the island.

Guess, either the construction troops did not use latrines and "held it in," or else, their latrines were exquisitely constructed - thus not considered to be simple "latrines."

[Delta Tank]

Hindsight is always 20/20...

They knew or had a pretty good idea how large the garrison was. Why attack where you know where the enemy is, when you can seize/occupy islands where the enemy is not? Example Abemama, seized by a company (-) with very few casualties.

And then we repeated this mistake at Peleliu.

Mike

And the garrison was underestimated by approximately half.

Abemama was fine for the large bombers. However, you could not further cram the medium bombers and fighters onto the same airfield.

From the book entitled “Aleutians, Gilbert’s and Marshalls June 1942-April 1944” by Samuel Eliot Morison, printed in 1951, page 149: “Betio had been so thoroughly reconnoitered by aircraft and submarine that the Japanese defenses were well known in advance to the officers entrusted with its capture. Even the number of defenders had been estimated correctly, to within a hundred men.” Footnote #5 will not type it in but it discusses the latrine method of 64 men per hole.

So, we DID NOT underestimate by approximately half.

Mike

Ummm...Estimates ran from 2,600-3,200. When there were 4,600 on the island.

Guess, either the construction troops did not use latrines and "held it in," or else, their latrines were exquisitely constructed - thus not considered to be simple "latrines."

Takao,

So, you are stating that what Samuel Eliot Morison wrote is false and your sources are??? Credible sources?

Mike

[Takao]

For starters...The United States Marine Corps
https://www.google.com/url?sa=t&source= ... SB2iAXb_Fn

Unless you do not consider the USMC to be credible.

The NHHC
https://www.history.navy.mil/content/hi ... 025-1.html
But, they are about as credible as the Marines.

[Takao]

Now...Show me US Intelligence reports showing that there were within 100 of 4,609 Japanese forces on Betio.

[Kingfish]

For starters...The United States Marine Corps
https://www.google.com/url?sa=t&source= ... SB2iAXb_Fn

Unless you do not consider the USMC to be credible.

The NHHC
https://www.history.navy.mil/content/hi ... 025-1.html
But, they are about as credible as the Marines.

Can you quote from either source the estimated number of troops?
I didn't see anything suggesting we underestimated the total.

[Takao]

Most of the Japanese in Tarawa Atoll were believed to be on Betio and the estimated strength of the garrison on that island was placed at 2,500 to 2,700 men. This was later revised to not less than 2,700 men and not more than 3,100. 
https://www.ibiblio.org/hyperwar/USMC/U ... awa-1.html

[Carl Schwamberger]

Alexander 'Utmost Savagery' actually lists the Naval Intelligence Report in his Bibliography, that is the document the assigned fleet constructed & which was used by the Amphib Corps/2d Marine Division as the basis for the Intelligence Annex of their operational and landing plan. This is opposed to the official USN histories which most histories seem to be drawing from. The 4,600 man estimate looks suspiciously like one of the post battle estimates made from information gathered by the 2d Division G2 & the amphib corps G2. That was drawn from counting corpses, interrogation of Warrant Officer Ota, and early translation of documents gathered around Betio. Unfortunately these intel annexes from the landing plans are not reproduced in any thing I have on the shelf.

The most accurate eyewitness account might be Shoups papers. As the 2d Division G3 he wrote the landing plan for the division & would have read the intel information throughly.

Intial intelligence for Betio was drawn from analysis of japanese radio messages, which did include strength reports for units. However not all messages were intercepted. & the garrison was reinforced several times in 1943. Alexander notes that the labor unit came in two components. The initial group was of skilled laborers, including electricians, surveyors, draftsmen carpenters. The second group are described as the laborers. Its also noted a battalion of 600 Army was to replace a porthion of the SNLF men, but their transport was torpedoed and damaged, leaving them stranded far to the west.

None of the descriptions of the estimates I've read reproduce the estimates for weapons. Tho there were estimates made from knowledge of the SNLF organization, and from the air photographs. Alexanders text suggests the estimates of the crew served weapons matches that of US understanding of a SNLF organization, but its not clear from any of the histories I've seen if the reinforcing units weapons were counted accurately. It seems to have been understood the SLF unit was reinforces with additional cannon and anti aircraft HMG but precise numbers are lacking. Alexander remarks that the 2d Divisions G2 Situation Map was judged 90% accurate but again does not go into detail. Post war Japanese documents (probably not all) were found in Japan repeating to Betios defenses. Alexanders mentions a translation of those.

I have to say I am drawing from a paper back copy of Utmost Savagery, which may not be complete. Publishers frequently butcher those deleting annexes maps and photos from the original hard back editions.

[Carl Schwamberger]

Tides

May as well address that or Alexanders remarks on it. First he points out prewar data from Tarawa & the Gilberts in general was contradictory. This includes British & New Zealander businessmen who have visited or lived in the Gilberts. A New Zeeland Reserve officer Frank Holland was attached to the 2d Divisions staff & did warn of the possibility of a extraordinarily low tide. Others are described as stating the tide would be reliable. The relatively low normal tide depth of four feet was noted in the initial planning conference and discussed in subsequent meetings that month. From experience Shoup and the other leaders knew that coral reef depths were not consistent & 'four feet' would be a mean depth with unknown variations. This led to the understanding the risk of permanently grounded landing craft part way across the reef & a portion of the assault force might have to wade the reef. It also reinforced the idea of converting the LVT available from supply trucks to assault weapons. The decision for that seems to have been broached in the initial conference, and was turned into a formal directive within a fe days. A related decision was to use the rubber boats and training provided to three of the divisions battalions.

Survivors and others have pointed out that had the tide been full at H hour the narrow beach and seawall would have been flooded, depriving the marines of any cover. The japanese had a interlocking band of enfilading fire from their MG covering the ground adjacent to the tide line. This ground was cleared of brush and most other obstacles making for a bare strip several meters wide. That was backed by a trench zone of multiple trenches where the rifle squads were positioned when the assault landed. However the MG & rifle positions did not enfilade the narrow strip of beach behind the seawall. A flooded seawall means the assault teams debouching from the LVT & landing craft would not have the benefit of that dead ground.


Alexander also cites a analysis by Donald Olsen of the Texas State University of the Tarawa atoll tides. Published in Sky and Telescope magazine 1987 as "The Tide at Tarawa' Olsen demonstrates the combination of the well understood twice monthly neap tide created by the Moon, and of the near unknown effect of the Moons orbit twice yearly. That is when at maximum distance in its orbit the tidal effect in decreased. The landing date at the Tarawa atoll coincides with both the common neap tide and the rarer apogean tide. Olsen calculate this would have occurred twice in 1943. First in April and again 19 November.

That a unfavorable wind caused the low water seems to have first come from Sec nav Know in a post battle press conference. I've not seen that attributed reliably to anyone closer to the battle.

[Felix C]

Do not know if accurate I read in a mid 70s work where a 1943 central pacific thrust commencing at the Marshall islands and the naval commander in charge indicated he wanted to attack the Gilberts first so as not to have is flank exposed to attack from there. Will get more info and update this post with names.

[Carl Schwamberger]

A fast glance at the map makes the flank protection idea clear.