X-Day: Phoenix Caisson?

[ArmchairSamurai]

Hello all. After I reviewed the documentation provided by https://www.cia.gov/library/center-for- ... html#rtoc3 and the accompanying PDF on the considerations, preparations, and SIGINT data for the invasion of Japan planned for November 1945, I immediately looked for comparisons between the X-Day landings and what was learned from D-Day. With that being said, is it reasonable to postulate that the Phoenix Caissons would have been used once more at Kyushu? Japan's navy was virtually eliminated by 1945 and no viable threat aside from kamikazes existed elsewhere to intercept the caissons from the staging ground to Kyushu. I would, however, expect the Japanese to either mine all ports available to the invasion force or purposefully sink vessels in the ports to deny their use. On the other hand, the distance from Okinawa to Kyushu is almost three times farther than from West Sussex / Kent to Normandy. What do you all think? I appreciate your opinions. Much obliged.

[Carl Schwamberger]

These caissons used up a lot of concrete & steel & required a ocean going tug boat each while in transit. @ 2-3 knots. Thats a lot of resources. Any evidence the US or Brits but any or studied their possible use?

[Mil-tech Bard]

Try looking for "Project DAGWOOD."

DAGWOOD was to build the pontoons/caissons for DOWNFALL.

It is mentioned in "Marinship: The History of a Wartime Shipyard" pages 367 to 370.

[ArmchairSamurai]

Try looking for "Project DAGWOOD."

DAGWOOD was to build the pontoons/caissons for DOWNFALL.

It is mentioned in "Marinship: The History of a Wartime Shipyard" pages 367 to 370.

I very, very much appreciate the contribution Mil-tech Bard. I thought this thread was dead. I managed to track down Marinship's archives to the San Francisco Maritime National Historical Park and I am currently waiting to hear back from the staff on its collection.

https://oac.cdlib.org/findaid/ark:/13030/c8sb46zn/

[Pips]

Really keen to hear what you find out ArmchairSamurai. Towing pontoons from Okinawa to Kyushu does not seem practicable.

[ArmchairSamurai]

Really keen to hear what you find out ArmchairSamurai. Towing pontoons from Okinawa to Kyushu does not seem practicable.

I am back. I have found what I set out to find. The funny thing is, after contacting the San Francisco Maritime National Historical Park, The Sausalito Historical Society and even Bechtel themselves, then the author of WORLD WAR II SHIPYARDS BY THE BAY, Nicholas A. Veronico, it all led me back to Mil-Tech Bard's earlier suggestion. How ironic. See, I figured said suggestion was simply another book, or compilation if you will, of information and certainly not the *source* everyone else was crediting in their work. I overlooked it. That being said, Veronico, the author I mentioned, gave me this from his copy of "Marinship: The History of a Wartime Shipyard":

https://imgur.com/P7ksO2m

https://imgur.com/vKSN2EM

https://imgur.com/LRd8ifl

I am buying a copy myself, and may post the blueprints for Dagwood at a later date.

Cheers!

[Mil-tech Bard]

I'm glad that resource worked out for you, ArmchairSamurai.

FYI, a research buddy of mine found that LAST GREAT VICTORY by Weintraub mentioned Dagwood on P.287.

His comment:

"The Navy had a secret project named DAGWOOD that was #1 in priority -- it was basically right after the Manhattan project in getting stuff."

It is also showed up in the "COMINCH S74 secret files NARA II for 1945" under another code name, IRON HORSE.

Again his comment:

DAGWOOD was a lower level code name for IRON HORSE. Only thing with more priority than IRON HORSE was Manhattan. Complete preliminary IRONHORSE circular proposal put forth in August 1945 with calculations and diagrams to be used as a basis for detailed engineering studies by buships

[ArmchairSamurai]

Hello again Mil-tech Bard!

Would you happen to know if the "COMINCH S74 secret files NARA II for 1945" is available anywhere online?

I would rather enjoy reading that if it were available.

Perhaps the Library of Congress?

I know you got this information from a friend, yet it wouldn't hurt for me to ask just to be clear.

[Mil-tech Bard]

They are in NARA.