Date of D-Day if the Allies want to land at high tide

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Carl Schwamberger
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Re: Date of D-Day if the Allies want to land at high tide

Post by Carl Schwamberger » 11 Apr 2021 19:13

Sheldrake wrote:
11 Apr 2021 10:21
I don't disagree with your analysis, but would like to add in another factor- recovery time allowed to the defenders.
Yes, I mentioned it:
]Second is a very short time between the end of the 'Suppressive' attack and the arrival of the assault. In a perfect world the first assault squad touches the enemy trench or bunker one second after the fragments of the last projectile/bomb hit it.
Sheldrake wrote:
11 Apr 2021 10:21
By 1944 it was known that the suppression effect from artillery bombardments lasted for no more than 2 minutes. Unless the infantry closed with the defenders this time, German (or Japanese) would have recovered from the suppressive effects. This was known as long ago as 1916 but seems to have been one of those things lost in peacetime. The implications are that the infantry would need to be well within 200 metres/yards of the enemy before the last rounds hit the target.
This is where definitions, technical, language, or semantics break down. The rules we used circa 1983-1997 for fire planning considered 'Suppression' to only occur while the projectiles were actually falling, and ceasing very shortly after. Inside the two minutes referred to above. The other level 'Neutralization' we were considering as defined by:
Enemy in the target area is unable to effectively fire or maneuver long enough for the attacker to move to assault, or maneuver past, the target area.
We considered 3-6 % casualties necessary for a proper nuetralization. Now for a couple subtle points we observed in our effects tables/descriptions. One was the larger the projectiles/bombs the longer the Neutralization was expected to last. Second was casualties are also defined by ear damage and concussion from overpressure. Folks lose sight of those because they are quickly recoverable injuries. Soldiers suffering from overpressure concussion or ear damage usually return to 70-80 %+ effectiveness in fifteen or twenty minutes. Less if the projectiles are small, like 81mm mortar, as 25lbr, or 105mm round; longer if its a 8" round, a 500 or 1000 pound bomb. I found a remark on guidance from the US AAF given in the Ninth AF for attack planning in latter 1944 that a entrenched defenders should be considered recovered from medium bomber attack 45 minutes after the las bomb. My father who spent February through April as a air liaision officer with first army remembered the rule being 20 minutes for suppression effects to linger to the attackers benefit.

So, lets consider if Dolittles bombers release on target & achieve reasonable concentrations on & around the Resistance Nests. With the mix being predominately 250lb bombs. Thats not going to crack many bunkers, if any at all, but it does impart some level of concussive and deafeinig overpressure effects on the defenders. If the mix is all 500 & 1000 lb bombs it looks like the concussive effect would be longer lasting.

So, theres not likely enough maimed defenders to fall into the 'Neutralized' category I was trained to, so they are Suppressed except the temporary incapacitation lasts out 20 minutes or better which is better than Suppressed.

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Re: Date of D-Day if the Allies want to land at high tide

Post by Sheldrake » 11 Apr 2021 19:59

rcocean wrote:
11 Apr 2021 17:36
BTW, I know that in the Pacific standard procedure was to drench the beach with rocket fire just before the first wave hit. This was developed since the gap between the gunfire lifting and the Troops hitting the beach allowed the Japanese to recover. Another naval commander mentioned that on Kwajalein instead of the gunfire lifting at a certain time, a plane would drop colored flares when the LCT's were about to hit the beach, which was the signal for the gunfire to lift. I guess that wasn't done on June 6th.
There was a lot wrong with the idea of dropping coloured flares to stop the barrage, It does not follow the failsafe approach. It will go horribly wrong something happens to the aircraft or bad weather prevents the ships seeing the flares or someone else fires similar flares. A timed fireplan is the best approach. An overflying observer with the authority to extend the fireplan might work better.

Rockets are less accurate than artillery or naval gunfire so they tend to be fired before the NGS stops - as on D Day

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Re: Date of D-Day if the Allies want to land at high tide

Post by Sheldrake » 12 Apr 2021 00:43

Carl Schwamberger wrote:
11 Apr 2021 19:13
Sheldrake wrote:
11 Apr 2021 10:21
I don't disagree with your analysis, but would like to add in another factor- recovery time allowed to the defenders.
Yes, I mentioned it:
]Second is a very short time between the end of the 'Suppressive' attack and the arrival of the assault. In a perfect world the first assault squad touches the enemy trench or bunker one second after the fragments of the last projectile/bomb hit it.
Sheldrake wrote:
11 Apr 2021 10:21
By 1944 it was known that the suppression effect from artillery bombardments lasted for no more than 2 minutes. Unless the infantry closed with the defenders this time, German (or Japanese) would have recovered from the suppressive effects. This was known as long ago as 1916 but seems to have been one of those things lost in peacetime. The implications are that the infantry would need to be well within 200 metres/yards of the enemy before the last rounds hit the target.
This is where definitions, technical, language, or semantics break down. The rules we used circa 1983-1997 for fire planning considered 'Suppression' to only occur while the projectiles were actually falling, and ceasing very shortly after. Inside the two minutes referred to above. The other level 'Neutralization' we were considering as defined by:
Enemy in the target area is unable to effectively fire or maneuver long enough for the attacker to move to assault, or maneuver past, the target area.
We considered 3-6 % casualties necessary for a proper nuetralization. Now for a couple subtle points we observed in our effects tables/descriptions. One was the larger the projectiles/bombs the longer the Neutralization was expected to last. Second was casualties are also defined by ear damage and concussion from overpressure. Folks lose sight of those because they are quickly recoverable injuries. Soldiers suffering from overpressure concussion or ear damage usually return to 70-80 %+ effectiveness in fifteen or twenty minutes. Less if the projectiles are small, like 81mm mortar, as 25lbr, or 105mm round; longer if its a 8" round, a 500 or 1000 pound bomb. I found a remark on guidance from the US AAF given in the Ninth AF for attack planning in latter 1944 that a entrenched defenders should be considered recovered from medium bomber attack 45 minutes after the las bomb. My father who spent February through April as a air liaision officer with first army remembered the rule being 20 minutes for suppression effects to linger to the attackers benefit.

So, lets consider if Dolittles bombers release on target & achieve reasonable concentrations on & around the Resistance Nests. With the mix being predominately 250lb bombs. Thats not going to crack many bunkers, if any at all, but it does impart some level of concussive and deafeinig overpressure effects on the defenders. If the mix is all 500 & 1000 lb bombs it looks like the concussive effect would be longer lasting.

So, theres not likely enough maimed defenders to fall into the 'Neutralized' category I was trained to, so they are Suppressed except the temporary incapacitation lasts out 20 minutes or better which is better than Suppressed.
Interesting points.

We can get tied up in definitions and any precision about the distinction between suppression, neutralisation and destruction. There is a relationship between the intensity of a bombardment and the length of time those underneath it are rendered incapable on defence. That intensity may be psychological or, as you suggest, temporary physiological damage - back to the WW1 era concept of shell shock.

There is the temporary neutralisation of defenders hiding from a field artillery bombardment. This is the 2 mins from WW1 and WW2 experience, requiring a close follow up by troops with grenade and bayonet. There was also a longer period of around 45 minutes numbness from the heavier bombardments typically delivered by air. This was noted in Op Goodwood and ties in with your quoted comments from 9th AF. Here the level of energy released is close to a tactical nuclear weapon. 100 Lancaster bombers each dropping 6 tons of HE on a village is 0.6Kt yield in nuclear fire planning terms..

The D Day fire plan did use large numbers of heavy bombers, but about fifty targets were assigned to one or two "squadrons" each of six aircraft across forty miles. Sixteen 250 bombs from a B17 or B24 is about three tons of HE so a target might have received 36 tons of HE - an order of magnitude smaller than the bombardments delivered in support of Ops Good Wood, Cobra, Totalize and Tractable. Only the bombardment of W5 on Utah Beach by B26s noticeably suppressed the defenders.

There is also the randomness of results

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Re: Date of D-Day if the Allies want to land at high tide

Post by Carl Schwamberger » 12 Apr 2021 02:44

Sheldrake wrote:
12 Apr 2021 00:43
The D Day fire plan did use large numbers of heavy bombers, but about fifty targets were assigned to one or two "squadrons" each of six aircraft across forty miles. Sixteen 250 bombs from a B17 or B24 is about three tons of HE so a target might have received 36 tons of HE - an order of magnitude smaller than the bombardments delivered in support of Ops Good Wood, Cobra, Totalize and Tractable. Only the bombardment of W5 on Utah Beach by B26s noticeably suppressed the defenders.

There is also the randomness of results
Never done a density analysis between those. The smaller the target surface area per kg of explosive the greater the effect. This is the same for time. I don't recall from out fire planning a expression for the two measurements combined.

W5 is interesting for a variety of reasons. One being the higher than planned concentration of bombs. It looks like a large portion of the bombers missed the landmarks or IP for their targets & dumped on W5 as it was last in line before the unmistakable landmark of the Vire estuary. It also looks like the defenders of W5 were better classified as Neutralized in the terms I'm familiar with. 5%+ casualties, the 88 & several MG inoperable, the defenders described as disoriented and panicked.

One summary of the 9th AF post attack survey states 341 bombers sortied, 48 aborted, or failed to ID a target, & two collided during assembly. 293 attacked from 6.000' or less. Like the OMAHA Beach attack the 250 lb bomb predominated. The post battle examination claimed 59% landed within 500 meters of a target & 16% were counted as direct hits. What I don't have is the map that shows how that 59 & 16 percents were weighted towards the W5 target. Or the number and location of the total targets. The air crew accounts and other 9th AF sources state the attack formed into 54 plane Groups and 18 plane boxes, but don't identify how they were organized for the attack. In those groups & boxes, or something else? How many bombers per specific target?

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Re: Date of D-Day if the Allies want to land at high tide

Post by Sheldrake » 12 Apr 2021 09:20

Carl Schwamberger wrote:
12 Apr 2021 02:44
W5 is interesting for a variety of reasons. One being the higher than planned concentration of bombs. It looks like a large portion of the bombers missed the landmarks or IP for their targets & dumped on W5 as it was last in line before the unmistakable landmark of the Vire estuary. It also looks like the defenders of W5 were better classified as Neutralized in the terms I'm familiar with. 5%+ casualties, the 88 & several MG inoperable, the defenders described as disoriented and panicked.

One summary of the 9th AF post attack survey states 341 bombers sortied, 48 aborted, or failed to ID a target, & two collided during assembly. 293 attacked from 6.000' or less. Like the OMAHA Beach attack the 250 lb bomb predominated. The post battle examination claimed 59% landed within 500 meters of a target & 16% were counted as direct hits. What I don't have is the map that shows how that 59 & 16 percents were weighted towards the W5 target. Or the number and location of the total targets. The air crew accounts and other 9th AF sources state the attack formed into 54 plane Groups and 18 plane boxes, but don't identify how they were organized for the attack. In those groups & boxes, or something else? How many bombers per specific target?
IRRC 9th AF were responsible for the targets on UTAH Beach and two (?) on the eastern Flank of the invasion force. 8th AF for the targets on the coast between the Vire and Dives rivers - Omaha to Sword. 8th AF bombed through cloud using H2X air to ground radar. 9th AF used visual bombing from a much lower height - 7,000 feet. The attacks on the targets were led by RAF Pathrfinder aircraft fitted with Gee but these failed to find their assigned targets.

My source for the numbers of bombers per target is the Second Army Fireplan, and the correspondence between that HQ and the USAAF. The fireplan says how many aircraft were going to attack each target, and the correspondence included a request from 8th AF for sketches of each target. I don't know how the 8th AF assigned targets to each squadron but I recall reading that one bombardment division attacked targets on and behind Omaha Beach and the other two targets behind Gold,Juno and Sword. I don't think that the skill and bombing accuracy achieved by 8th AF on D Day has been adequately recognised. They had spent the last year learning to bomb by day as Group sized formations on targets the size of a grid square On 6th June they bombed by squadrons through cloud on much smaller targets.

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Re: Date of D-Day if the Allies want to land at high tide

Post by Carl Schwamberger » 12 Apr 2021 12:08

Sheldrake wrote:
12 Apr 2021 09:20
Carl Schwamberger wrote:
12 Apr 2021 02:44
W5 is interesting for a variety of reasons. One being the higher than planned concentration of bombs. It looks like a large portion of the bombers missed the landmarks or IP for their targets & dumped on W5 as it was last in line before the unmistakable landmark of the Vire estuary. It also looks like the defenders of W5 were better classified as Neutralized in the terms I'm familiar with. 5%+ casualties, the 88 & several MG inoperable, the defenders described as disoriented and panicked.

One summary of the 9th AF post attack survey states 341 bombers sortied, 48 aborted, or failed to ID a target, & two collided during assembly. 293 attacked from 6.000' or less. Like the OMAHA Beach attack the 250 lb bomb predominated. The post battle examination claimed 59% landed within 500 meters of a target & 16% were counted as direct hits. What I don't have is the map that shows how that 59 & 16 percents were weighted towards the W5 target. Or the number and location of the total targets. The air crew accounts and other 9th AF sources state the attack formed into 54 plane Groups and 18 plane boxes, but don't identify how they were organized for the attack. In those groups & boxes, or something else? How many bombers per specific target?
IRRC 9th AF were responsible for the targets on UTAH Beach and two (?) on the eastern Flank of the invasion force. 8th AF for the targets on the coast between the Vire and Dives rivers - Omaha to Sword. 8th AF bombed through cloud using H2X air to ground radar. 9th AF used visual bombing from a much lower height - 7,000 feet.
Haven't yet found any air crew who bought they attacked from above five or six thousand feet. Some described a lot lower as the cloud bottom was varying & a portion had to drop further down to see the landmarks and targets.
Sheldrake wrote:
12 Apr 2021 09:20
The attacks on the targets were led by RAF Pathrfinder aircraft fitted with Gee but these failed to find their assigned targets.
A detail usually left out of the descriptions.
Sheldrake wrote:
12 Apr 2021 09:20
I recall reading that one bombardment division attacked targets on and behind Omaha Beach and the other two targets behind Gold,Juno and Sword.
The attacks on those targets is under studied in the popular histories. The volume on JUNO Beach on my shelf makes some passing reference to the damage from the air strike, but little else.

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Re: Date of D-Day if the Allies want to land at high tide

Post by Richard Anderson » 12 Apr 2021 16:17

Sheldrake wrote:
12 Apr 2021 09:20
IRRC 9th AF were responsible for the targets on UTAH Beach and two (?) on the eastern Flank of the invasion force. 8th AF for the targets on the coast between the Vire and Dives rivers - Omaha to Sword. 8th AF bombed through cloud using H2X air to ground radar. 9th AF used visual bombing from a much lower height - 7,000 feet. The attacks on the targets were led by RAF Pathrfinder aircraft fitted with Gee but these failed to find their assigned targets.
See, [url]file:///C:/Users/richt/AppData/Local/Temp/p4013coll8_2872.pdf[/url] pages 50-51 for the Ninth Air Force bombing of the UTAH defenses in particular, but also the IX Bomber Command missions in general on D-Day.

See, https://cgsc.contentdm.oclc.org/digital ... 4859/rec/1 for the Eighth Air Force D-Day effort, especially [PDF] page 236-248 for details on the 1st Mission on D-Day (the beach drenching mission) and [PDF] pages 266-277 for the post-battle analysis.
"Is all this pretentious pseudo intellectual citing of sources REALLY necessary? It gets in the way of a good, spirited debate, destroys the cadence." POD, 6 October 2018

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