Expertise from Pacific used for Overlord

[ivanotter]

I have not seen any 'comparing of notes' between the planners of Overlord and the Pacific commanders (Turner springs to mind).

How much consultation happened? Re-reading Brooke's it seems as though there was nothing to be gained from consulting the Pacific experiences.

Okinawa was later than Overlord and it was Turner's 5th invasion across the beaches.

It does come across as though the Pacific was less elaborate and more 'on the fly' landings. That might be unfair, though.

Therefore:
Put Turner (or maybe a host of the admirals and the USMC generals) in to plan and do the landings and then the build-up from there as OTL.

Could it work? would it be better? faster? less bloody?

Or were there substantial differences between the Japanese way and the German way of fighting the landings?

 

[CalBear]

There were limited actual lessons available from the early war opposed landing that could be applied to Overlord.

The single biggeast lesson is that whatever you though was too much pre-landing bombardment is way too little If you thing a day is enough go for four days if it's a week, cut the location off from reinforcement had hammer it for weeks, both with bombing and a LOT of heavy naval gunfire against a relatively narrow target zone with the bombardment lasting until the landing forces are 20 minutes out from the beach, with aircraft hammering everything sticking out of the ground until the troops actually reach the surf zone, followed by aircraft being ready for instant "on-call" strikes against targets.

Pretty much all of that is a disaster waiting to happen against a continental target. You spend a couple weeks hammering a 10 miles of beach defenses on a continuous basis you may as well send out invitations. While that isn't an entirely bad thing, assuming you have enough firepower to do it a couple times before actually landing, since it allows you you to use massive firepower to degrade enemy mobile forces before making the actual attempt, and if you have essentially a continuously open window for conducting the landings. Unfortunately Overlord only had around a 3 day window each month where tides and phases of the Moon lined up, and while prodigious, WAllied naval gunfire support was finite (as an example, the USN 14" gun had a barrel liner life of ~200 rounds, the RN 15" design was limited to 250 round of HE, after this limit the barrels would require relining)

As an example, Overlord (more properly Operation Neptune), for all five beaches, had a not insignificant naval gunfire group that included six battleships, two Monitors (each with a singe two gun 15"/42 turret), five heavy cruisers and 17 light cruisers to handle gunfire support for a total coastline that stretched over forty miles from the edge of Utah to the for edge of Sword. while not all the distances was actually landing beaches, it all had to be covered inland from the surf zone to 10 miles/17,000 meters inland. Pre-landing bombardment commenced 40 minutes prior to landing in order to preserve tactical surprise. That is a big job to complete in under an hour.

At virtually the same time (June 15th) in the Pacific the U.S. assaulted Saipan. The total landing Frontage was about four miles on an Island that every ship in the gunfire support force could reach with gunfire without actually having to move the ship. The gunfire support units assigned to Saipan included 9 battleships (including two fast BB, Indiana and Washington that were detached from the fast carrier force from June 13-15), 6 CA and 7 CL.This force bombarded the landing beaches for 3 1/2 days; post battle the Marine Ground commander stated that that was an insufficient time to properly prepare four miles of beach. In addition the concentrated 3 1/2 days of bombardment, all six fast BB of TF 58 spend June 12 bombarding Japanese positions and runways. This was possible since the nearest Japanese infantry reinforcement was 900 mile away and TF 58 sat between Peleliu and the Marianas.

What could have been "ported" over to Overlord was the close air support methods used by USN and USMC fighter-bombers, TBF bombers and close air support landing teams who operated from the escort carrier force and had become specialists in "danger close" and specific infantry support missions since CAS and ASW were ALL THEY DID. While the WAllies assigned a huge number of squadrons to provide air support the pilots of those aircraft were not dedicated to supporting the landing force (for the obvious reason than there was exactly one invasion of France to support) with most of the support units being regular fighter squadrons and fighter bomber forces that routinely did deeper interdiction, not the up close and personal methods in the Pacific. It must, however, be noted, that the weather for Overlord was fairly disgusting, with extremely poor flying weather that reduced the ability to support troops on the beach. The Army and Marine naval gunfire support teams in the Pacific, for similar reasons to the CAS elements were also in general more effective than those at Normandy.

The one truly GLARING failure in planning D-Day was the decision NOT to use amtracs. This because especially problematic when the majority of the Sherman DD tanks actually launched sank in the rough waters off the beach (the 741st launched 29 DD tanks, 27 sank), denying the landing forces organic 75mm gunfire support until the LST were able to put the tanks directly over the beach via ramp. The addition of 100 LVT(A) to the Omaha landing force would likely have gotten the landing force off the beach by 08:30 since their 75mm howitzers could have cleared the obstacles from the beach exits and provided suppressive fire against at least some of the clifftop positions. It would likely have been better to do a 100% LVT landing, especially the versions with the rear ramp (the LVT-4 introduced in 1943), which would have reduced the "sitting duck" effect that all too frequently happened on Omaha when LCI dropped their ramps directly in front of MG-42 positions. The Buffaloes would also have been able to add considerable belt fed machine gun support to the first wave and perhaps second wave when LCI/LCVP could have served to land later waves.

 

[Pete55]

This biggest difference between the two types of assault is of course the little problem of Germany being able to schlep a dozen divisions into the area within weeks. The other issue that complicates things is the multi national force doing the invading. The Americans for instance absolutely used lessons from the Pacific to some degree. Some items had simply become a part of doctrine, especially regarding pre invasion BB fire. It isnt like the British have the same lessons scrawled into ther notebooks without a complex liaison training.

That said, the ideal case would have been the Americans being able to bring their Pacific forces to bear in operation Neptune. This would have allowed enough American Amphibious rated divisions to assault all five beaches, simplifying the assault while letting the British and Canadians focus on breaking out. Remember, the British and Canadians used 2 divisions to hit he beaches and one to jump behind the lines. The marines can certainly fill at least the 1st two roles.

The Glut of trained and veteran in type heavy naval assets would have worked wonders on the various coastal fortifications and batteries, and the CAS/gunfire support would likely have subdued the deadly blockhouses in a much more timely manner.

----

The issue that comes up is the Marines lack of maneuver warfare experience and their corresponding lack of experience against mass armor. The Bocage countrynis right up their alley, but massed armor is not.

 

[Aber]

The Americans for instance absolutely used lessons from the Pacific to some degree. Some items had simply become a part of doctrine, especially regarding pre invasion BB fire. It isnt like the British have the same lessons scrawled into ther notebooks without a complex liaison training.

And yet by comparison the British landings worked out better...

 

[steamboy]

In @Sbiper 's superb Reap the Whirlwind the main character of the story (in the body of Sir Arthur Harris of bomber command) he has Bomber Command hit the beaches with a heavy raid as the troops are approaching the coast, using large numbers of cookies and other GP bombs dropped from fairly low altitude and onto the defenders heads, along with a decent mix of incendiaries. Of course this couldn't happen OTL because if you suggested using either the 8th Airforce or Bomber Command in direct support of the Army then the REEEEEEEEE of outrage would be audiable from beyond the orbit of Neptune. But more direct support like the US Marines had from air would have definately been better.

@CalBear IIRC the issue with Amtraks was more resource allocation than them actively avoiding them and that it was more due to people like Marshall viewing them as Marine equipment, and considering his views on Marines, putting anything of theirs would probably get him gnawing his way through his desk. It was, I belive a case that 'they're allocated for the pacific so that's where they stay' kind of mindset. Obviously the totally wrong one!

 

[vizzer]

Also in the case of Amtraks if they're launched as far out as the DD Shermans they'll probably take similar losses, reduced somewhat by being a bit more seaworthy.

 

[Aber]

Of course this couldn't happen OTL because if you suggested using either the 8th Airforce or Bomber Command in direct support of the Army then the REEEEEEEEE of outrage would be audiable from beyond the orbit of Neptune.

But 8th Air Force DID attack the beach defences from 10,000 feet on D-Day just before the landings.

https://www.b24.net/D-day.htm

 

[steamboy]

But 8th Air Force DID attack the beach defences from 10,000 feet on D-Day just before the landings.

https://www.b24.net/D-day.htm

I honestly didn't know that! Thanks for that

 

[Rickshaw]

The US Army in Europe were hopeless at planning an opposed landing. Whereas the British had learnt that they needed specialised armour to overcome obstacles and created the 79th Armoured Division, the US Army only reluctantly accepted the British offer of such equipment. It was mentioned that 27 DD tanks sank on the run into Normandy. Most of those were at the US beaches. The British put theirs ashore and they did their part quite well, suppressing and eliminating the German defences. They used flail and plow equipped tanks to clear mines and bobbin tanks to lay a path over the beaches. They had AVREs, bridge layers and Crocodile flame throwing tanks.

In the Pacific, the US Navy was equally as bad. They didn't see a problem with attacking the enemy head on and so ALL their landings were opposed. If instead that had chosen different beaches, islands, they would have achieved as much with far fewer casualties. They were thinking like Admirals who had last seen a land battle in WWI. Full ahead and damn the torpedoes. No specialised armour and no indirect approaches.

 

[EagleKeeper]

But 8th Air Force DID attack the beach defences from 10,000 feet on D-Day just before the landings.

https://www.b24.net/D-day.htm

Problem was the ceiling was about 6,000 feet so they held off hitting the pickle button for an extra few seconds and everything dropped inland of the beaches.. The Air Force also wasn't willing to fly parrallel to the coast but insisted on coming in from over the water (if parallel they wouldn't have thought it necessary to hold off the extra seconds to avoid hitting allied troops, Same mistake made some weeks later at the beginning of Cobra)

 

[EagleKeeper]

They did have one veteran of the Pacific who tried to make suggestions Pete Corlett who was scheduled for a Corps command. He found the Neptune planners to be very resistant to any suggestions and was generally ignored.

 

[McPherson]

There were limited actual lessons available from the early war opposed landing that could be applied to Overlord.

The single biggest lesson is that whatever you though was too much pre-landing bombardment is way too little If you thing a day is enough go for four days if it's a week, cut the location off from reinforcement had hammer it for weeks, both with bombing and a LOT of heavy naval gunfire against a relatively narrow target zone with the bombardment lasting until the landing forces are 20 minutes out from the beach, with aircraft hammering everything sticking out of the ground until the troops actually reach the surf zone, followed by aircraft being ready for instant "on-call" strikes against targets.

Pretty much all of that is a disaster waiting to happen against a continental target. You spend a couple weeks hammering a 10 miles of beach defenses on a continuous basis you may as well send out invitations. While that isn't an entirely bad thing, assuming you have enough firepower to do it a couple times before actually landing, since it allows you you to use massive firepower to degrade enemy mobile forces before making the actual attempt, and if you have essentially a continuously open window for conducting the landings. Unfortunately Overlord only had around a 3 day window each month where tides and phases of the Moon lined up, and while prodigious, W-Allied naval gunfire support was finite (as an example, the USN 14" gun had a barrel liner life of ~200 rounds, the RN 15" design was limited to 250 round of HE, after this limit the barrels would require relining)

As an example, Overlord (more properly Operation Neptune), for all five beaches, had a not insignificant naval gunfire group that included six battleships, two Monitors (each with a singe two gun 15"/42 turret), five heavy cruisers and 17 light cruisers to handle gunfire support for a total coastline that stretched over forty miles from the edge of Utah to the for edge of Sword. while not all the distances was actually landing beaches, it all had to be covered inland from the surf zone to 10 miles/17,000 meters inland. Pre-landing bombardment commenced 40 minutes prior to landing in order to preserve tactical surprise. That is a big job to complete in under an hour.

At virtually the same time (June 15th) in the Pacific the U.S. assaulted Saipan. The total landing Frontage was about four miles on an Island that every ship in the gunfire support force could reach with gunfire without actually having to move the ship. The gunfire support units assigned to Saipan included 9 battleships (including two fast BB, Indiana and Washington that were detached from the fast carrier force from June 13-15), 6 CA and 7 CL. This force bombarded the landing beaches for 3 1/2 days; post battle the Marine Ground commander stated that that was an insufficient time to properly prepare four miles of beach. In addition the concentrated 3 1/2 days of bombardment, all six fast BB of TF 58 spend June 12 bombarding Japanese positions and runways. This was possible since the nearest Japanese infantry reinforcement was 900 mile away and TF 58 sat between Peleliu and the Marianas.

What could have been "ported" over to Overlord was the close air support methods used by USN and USMC fighter-bombers, TBF bombers and close air support landing teams who operated from the escort carrier force and had become specialists in "danger close" and specific infantry support missions since CAS and ASW were ALL THEY DID. While the W-Allies assigned a huge number of squadrons to provide air support the pilots of those aircraft were not dedicated to supporting the landing force (for the obvious reason than there was exactly one invasion of France to support) with most of the support units being regular fighter squadrons and fighter bomber forces that routinely did deeper interdiction, not the up close and personal methods in the Pacific. It must, however, be noted, that the weather for Overlord was fairly disgusting, with extremely poor flying weather that reduced the ability to support troops on the beach. The Army and Marine naval gunfire support teams in the Pacific, for similar reasons to the CAS elements were also in general more effective than those at Normandy.

The one truly GLARING failure in planning D-Day was the decision NOT to use amtracs. This because especially problematic when the majority of the Sherman DD tanks actually launched sank in the rough waters off the beach (the 741st launched 29 DD tanks, 27 sank), denying the landing forces organic 75mm gunfire support until the LAST were able to put the tanks directly over the beach via ramp. The addition of 100 LVT(A) to the Omaha landing force would likely have gotten the landing force off the beach by 08:30 since their 75mm howitzers could have cleared the obstacle from the beach exits and provided suppressive fire against at least some of the clifftop positions. It would likely have been better to do a 100% LVT landing, especially the versions with the rear ramp (the LVT-4 introduced in 1943), which would have reduced the "sitting duck" effect that all too frequently happened on Omaha when LCI dropped their ramps directly in front of MG-42 positions. The Buffaloes would also have been able to add considerable belt fed machine gun support to the first wave and perhaps second wave when LCI/LCVP could have served to land later waves.

I generally agree with this analysis.

Specifically, though,
a. PACFLT did a much better job, after Tarawa, of beach recon at the surf line than SHAEF ever did. The reason for this difference was obvious, and it has nothing to do with SHAEF incompetence, because that was not the case or the reason. The British and the Americans could not risk tipping their hands as to what beaches they would hit with frogman recon swim-ins. So the sampling was spotty and incomplete. Aerial flyover could not show what OMAHA would turn out to be.
b. Gunfire support was measured in hours, not days. Guns have to cool down after a few dozen rounds or so or one risks barrel bursts. That 2 week bombardment of Iwo Jima was methodical. A battleship or cruiser might get a grid square and wait for an Avenger recon bird flyover to spot the interesting details and then the developed photos would wind up in the USS West Virginia and her fire control party would grid out where to put a few dozen shells over the course of two or three hours careful shooting per day.
c. LVTs at OMAHA? I've read that case made. OMAHA could have been bum rushed, the critics maintain. Well, that was tried at TARAWA. How did that work out? One cannot predict the surf conditions, and one cannot predict the opposition, but remember another beach like OMAHA, almost exactly like it for seawall, bluffs, tough Germans, and a channeled route and kill-box off the beach? If one had seen that beach (SALERNO, featured in the movie Wonder Woman as a stand-in for Themyscira), and if one was trained to read ground, one would know how easy a kill-sack that was for the Germans to set up. SALERNO was MUCH WORSE than OMAHA, because US destroyers could not work close in, there were far more Germans, and the Germans had air support. I have walked both beaches and I understood immediately how cruising into a bowl dominated by high ground and barely wider than machine gun cross fire could generate casualties of 25%. So, one cannot know if something different attempted could have marginally changed the result that much.
d. More than anything else about NEPTUNE, I have gripes about the wrong lessons learned as to air support. HUSKY and AVALANCHE had taught the Allied air commanders caution about unloading strategic heavy bombers and medium BIM bombers too close to the assault waves as they cruised into the surf line. The famous 30 second delay by the USAAF bombers as they made their runs in to avoid bombing the first waves of landing craft, and the lifting of the naval artillery 2 minutes prior to the final run-in and beaching might have been justified. Or it might not. I would have landed INTO the bombing and had the infantry take their chances. It could have been no worse than what happened during COBRA.

This biggest difference between the two types of assault is of course the little problem of Germany being able to schlep a dozen divisions into the area within weeks. The other issue that complicates things is the multi national force doing the invading. The Americans for instance absolutely used lessons from the Pacific to some degree. Some items had simply become a part of doctrine, especially regarding pre invasion BB fire. It isn't like the British have the same lessons scrawled into their notebooks without a complex liaison training.

e. I tend to think the mistakes in OVERLORD can be liberally spread around, but the British were less experienced and successful than the Americans. This was as much due to terrain and opposition post landings as it was due to inexperience with OVER THE BEACH supply and Marine style offensive operations. (Saipan, MG Ralph Smith is an example of how Marines hated being hung up by "the slows".)

That said, the ideal case would have been the Americans being able to bring their Pacific forces to bear in operation Neptune. This would have allowed enough American Amphibious rated divisions to assault all five beaches, simplifying the assault while letting the British and Canadians focus on breaking out.

f. Ehhh. I'm not sure even US Marines could have cleared CAEN as scheduled. It was a tough objective with horrible ground to traverse. Now Falaise Pocket? Marines would have closed that sack. And screw the boundary question.

Remember, the British and Canadians used 2 divisions to hit he beaches and one to jump behind the lines. The marines can certainly fill at least the 1st two roles.

g. See f.

The Glut of trained and veteran in type heavy naval assets would have worked wonders on the various coastal fortifications and batteries, and the CAS/gunfire support would likely have subdued the deadly blockhouses in a much more timely manner.

h. The use of dive bombers and NAPALM would be emphatically more effective than what happened.

----
The issue that comes up is the Marines lack of maneuver warfare experience and their corresponding lack of experience against mass armor. The Bocage country is right up their alley, but massed armor is not.

i. The German massed armor was against the Anglo Canadians. See f. again.

And yet by comparison the British landings worked out better...

k. The beaching at UTAH was a cakewalk. If the British had tried OMAHA, even with Hobart's Funnies they would have been cut to pieces just like the Americans were. So, let us put that myth to bed.

 

[vizzer]

How did the planning for the actual invasion of Japan compare with Overlord or was it more like the Pacific Island campaigns on a larger scale?

 

[Gannt the chartist]

There are probably no lessons to learn. The ETO has experience of Torch Husky Avalanche, Shingle already but the overall situation is totally different.

All the Invasions in the Pacific to date are against isolated garrisons, with limited supply and no hope of resupply or reinforcement unless the IJN sallies forth and Defeats the USN, Which they can try maybe twice before there is no IJN.

In Normandy the prospect is of about 7 Panzer Divisions being available immediately, Around 1,000 aircraft in Luftflotte 3 and the potential for that to be reinforced from central reserves or anywhere else in Europe on a few days notice far faster than seaborne reinforcement could arrive and be supplied. And you are a couple of days sail from the entire U boat arm so telegraphing the invasion is just not on, and invasion prep of the style used in the Pacific not feasible. So the allied forces have to interdict reinforcement fly cap and do a massive ASW and anti Mining operation throughout.

Overall the problem is not how do we storm the beaches but how do we stop a counterattack in the next day or so from a couple of Panzer armies.

fire control party would grid out where to put a few dozen shells over the course of two or three hours careful shooting per day

And generally miss. It is really hard to hit a target, even if you can identify it with predicted fire, comparatively easy with observed fire but that's a lengthy process with no certainty as to whether you have been successful until the position does not open fire later on. This is a lesson of WW1 that the US never learned. The immediate bombardment will not destroy even lightly hardened positions and if you are attacking without armour an MG will stop you dead until it is suppressed. What you can do is suppress the enemy for the length of the bombardment + maybe 2 minutes.

The beaching at UTAH was a cakewalk. If the British had tried OMAHA, even with Hobart's Funnies they would have been cut to pieces just like the Americans were. So, let us put that myth to bed.

See also JUNO which is very well documented. The Canadians there do a very different assault from OMAHA with a lot of direct fire support so its not just the funnies - though that would make a vast difference its also the light craft inshore from the start. Omaha is harder to be sure but a lot of the German positions remain intact until they run out of ammo on Juno there was a method in place to destroy them, whether it would have worked is another matter but the US did not even try.

I tend to think the mistakes in OVERLORD can be liberally spread around, but the British were less experienced and successful than the Americans

Jubilee. Torch Husky Avalanche, Baytown, Slapstick, Shingle, These are the experience of landing against significant forces. From the Pacific at this date, Tarawa? Most of the rest are much smaller scale and generally against very limited opposition.

LVTs at OMAHA? I've read that case made. OMAHA could have been bum rushed,

One also wonders where the LVT will come from and how they will get past the obstacles much less up the bluffs. OMAHA is actually a bad place unless you have direct fire available when the unsuppressed MGs open up. Whether thats from tanks or warships does not matter that much.

More than anything else about NEPTUNE, I have gripes about the wrong lessons learned as to air support

Disagree. There are too many variables in air support from the Heavies to make it precise. Everyone is working off different clocks with too many unknowns and the bombers will be taking off and forming over a long period before they are needed. The bombing parallel to the beach idea, Well who? the extreme flank of the formation, with everyone else bombing inland, or is it a line of bombers in column bombing over half an hour or more into increasingly obscured ground on the off chance a bomb will penetrate a reinforced bunker? with the invasion force circling around in range of an unknown number of guns shelling them and the unarmoured LST.

Most of the tactical aircraft who might be useable in a more precise way have to be used for CAP and in any case would conflict with any NGF.

f. Ehhh. I'm not sure even US Marines could have cleared CAEN as scheduled. It was a tough objective with horrible ground to traverse. Now Falaise Pocket? Marines would have closed that sack. And screw the boundary question.

So hows the Marines going to fare against 12th SS and 21st Panzer who are both in action late on 6th June. And this is the basic problem with talking about CAEN or the marines with very limited armour and artillery support going up against the single largest concentration of german armour ever assembled. Look at the frontage. They guys maybe but its not going to look at all like a WW2 Marine division.

The basic problems with the movement towards CAEN is while the Air forces want it for the airfields on day 1 so its in the plan its never really feasible. To pass through with enough force on a narrow front against first one KG of 21st panzer, then the rest then 12th SS over a fortress - HILLMAN with armoured cupolas capable of defeating direct hits from a 17lb. defended by a regiment is never going to be a walkover.

 

[McPherson]

So hows the Marines going to fare against 12th SS and 21st Panzer who are both in action late on 6th June. And this is the basic problem with talking about CAEN or the marines with very limited armour and artillery support going up against the single largest concentration of german armour ever assembled. Look at the frontage. They guys maybe but its not going to look at all like a WW2 Marine division.

That is the wrong question. How would the 12th SS and 21st fare against the 1st and 3rd US Marines? NTG. I don't have much respect for 1944 Panzergrenadiers. I have a lot of respect for 1944 Japanese diehards.

 

[Father Maryland]

There were limited actual lessons available from the early war opposed landing that could be applied to Overlord.

The single biggeast lesson is that whatever you though was too much pre-landing bombardment is way too little If you thing a day is enough go for four days if it's a week, cut the location off from reinforcement had hammer it for weeks, both with bombing and a LOT of heavy naval gunfire against a relatively narrow target zone with the bombardment lasting until the landing forces are 20 minutes out from the beach, with aircraft hammering everything sticking out of the ground until the troops actually reach the surf zone, followed by aircraft being ready for instant "on-call" strikes against targets.

Pretty much all of that is a disaster waiting to happen against a continental target. You spend a couple weeks hammering a 10 miles of beach defenses on a continuous basis you may as well send out invitations. While that isn't an entirely bad thing, assuming you have enough firepower to do it a couple times before actually landing, since it allows you you to use massive firepower to degrade enemy mobile forces before making the actual attempt, and if you have essentially a continuously open window for conducting the landings. Unfortunately Overlord only had around a 3 day window each month where tides and phases of the Moon lined up, and while prodigious, WAllied naval gunfire support was finite (as an example, the USN 14" gun had a barrel liner life of ~200 rounds, the RN 15" design was limited to 250 round of HE, after this limit the barrels would require relining)

As an example, Overlord (more properly Operation Neptune), for all five beaches, had a not insignificant naval gunfire group that included six battleships, two Monitors (each with a singe two gun 15"/42 turret), five heavy cruisers and 17 light cruisers to handle gunfire support for a total coastline that stretched over forty miles from the edge of Utah to the for edge of Sword. while not all the distances was actually landing beaches, it all had to be covered inland from the surf zone to 10 miles/17,000 meters inland. Pre-landing bombardment commenced 40 minutes prior to landing in order to preserve tactical surprise. That is a big job to complete in under an hour.

At virtually the same time (June 15th) in the Pacific the U.S. assaulted Saipan. The total landing Frontage was about four miles on an Island that every ship in the gunfire support force could reach with gunfire without actually having to move the ship. The gunfire support units assigned to Saipan included 9 battleships (including two fast BB, Indiana and Washington that were detached from the fast carrier force from June 13-15), 6 CA and 7 CL.This force bombarded the landing beaches for 3 1/2 days; post battle the Marine Ground commander stated that that was an insufficient time to properly prepare four miles of beach. In addition the concentrated 3 1/2 days of bombardment, all six fast BB of TF 58 spend June 12 bombarding Japanese positions and runways. This was possible since the nearest Japanese infantry reinforcement was 900 mile away and TF 58 sat between Peleliu and the Marianas.

What could have been "ported" over to Overlord was the close air support methods used by USN and USMC fighter-bombers, TBF bombers and close air support landing teams who operated from the escort carrier force and had become specialists in "danger close" and specific infantry support missions since CAS and ASW were ALL THEY DID. While the WAllies assigned a huge number of squadrons to provide air support the pilots of those aircraft were not dedicated to supporting the landing force (for the obvious reason than there was exactly one invasion of France to support) with most of the support units being regular fighter squadrons and fighter bomber forces that routinely did deeper interdiction, not the up close and personal methods in the Pacific. It must, however, be noted, that the weather for Overlord was fairly disgusting, with extremely poor flying weather that reduced the ability to support troops on the beach. The Army and Marine naval gunfire support teams in the Pacific, for similar reasons to the CAS elements were also in general more effective than those at Normandy.

The one truly GLARING failure in planning D-Day was the decision NOT to use amtracs. This because especially problematic when the majority of the Sherman DD tanks actually launched sank in the rough waters off the beach (the 741st launched 29 DD tanks, 27 sank), denying the landing forces organic 75mm gunfire support until the LAST wer able to put the tanks directly over the beach via ramp. The addition of 100 LVT(A) to the Omaha landing force would likely have gotten the landing force off the beach by 08:30 since their 75mm howitzers could have cleared the obstacle from the beach exits and provided suppressive fire against at least some of the clifftop positions. It would likely have been better to do a 100% LVT landing, especially the versions with the rear ramp (the LVT-4 introduced in 1943), which would have reduced the "sitting duck" effect that all too frequently happened on Omaha when LCI dropped their ramps directly in front of MG-42 positions. The Buffaloes would also have been able to add considerable belt fed machine gun support to the first wave and perhaps second wave when LCI/LCVP could have served to land later waves.

What do you think of the idea of the UK/ US saving at least some of the guns and turrets of warships scrapped as part of the Treaty in the 20s and come WW2 building a larger number of monitors for providing fire support closer in in shallower waters then the BBs and cruisers could get sort of like what the RN did in WW1 before or during WW2? Say at least a dozen " Heavies" mounting old BB guns ( Say 12 inch, 13 inch, 13.5 inch, and 14 inch guns and turrets) and a couple dozen lights and mediums mounting 5 inch, 6 inch, 7 inch, or 8 inch guns and turrets with the lights being able to get very close in to provide fire support sort of like but heavier then the destroyers fire that was ultimately used?

Would they have been worthwhile?

 

[Gillan1220]

Wasn't the landing in Tarawa used as a template for Overlord?

 

[marathag]

. If instead that had chosen different beaches, islands, they would have achieved as much with far fewer casualties

But some islands had to be taken, and some islands had limited areas where troops could go ashore

Sure some islands could have been bypassed, like Peleliu, with an samll airfield that just wasn't worth the lives spent in taken it.

But Guam and Tinian?
Those needed to be taken, even if not planning to invade the Philippines, they were needed for B-29 bases.

 

[marathag]

mediums mounting 5 inch, 6 inch, 7 inch, or 8 inch guns and turrets with the lights being able to get very close in to provide fire support sort of like but heavier then the destroyers fire that was ultimately used?

Would they have been worthwhile?

I've put out that some heavily armored shallow draft Monitors the size of the WWI Humber class monitors with 6" guns to get in closer than the DDs at Omaha eventually did, would have been a very good thing to have

 

[McPherson]

The US Army in Europe were hopeless at planning an opposed landing. Whereas the British had learnt that they needed specialised armour to overcome obstacles and created the 79th Armoured Division, the US Army only reluctantly accepted the British offer of such equipment. It was mentioned that 27 DD tanks sank on the run into Normandy. Most of those were at the US beaches. The British put theirs ashore and they did their part quite well, suppressing and eliminating the German defences. They used flail and plow equipped tanks to clear mines and bobbin tanks to lay a path over the beaches. They had AVREs, bridge layers and Crocodile flame throwing tanks.

Salerno.

In the Pacific, the US Navy was equally as bad. They didn't see a problem with attacking the enemy head on and so ALL their landings were opposed. If instead that had chosen different beaches, islands, they would have achieved as much with far fewer casualties. They were thinking like Admirals who had last seen a land battle in WWI. Full ahead and damn the torpedoes. No specialised armour and no indirect approaches.

Obviously this is not supported by the evidence. The whole concept of ISLAND HOPPING was based on bypass and starve out of such places like Rabaul and Chu'uk.