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

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

Post by Juan G. C. » 08 Apr 2021 18:00

Perhaps I should post this on thw What if section, so my apologies if it is in the wrong section. Initially the Allies wanted to land at high tide, so that the troops have less beach to cross under fire, but as Rommel put millions of obstacles under high tide, they decided that the initial landings would have to be made soon after low tide, to allow demolition groups to blow up enough obstacles to open corridors for the following landing craft. That is why they selected June 5, 6 and 7 as possible D-Days. But when would they have landed, if the germans hadn't put the obstacles and they had wanted to land at high tide? Which days would have met this and their other requirements?

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

Post by Richard Anderson » 08 Apr 2021 18:10

Juan G. C. wrote:
08 Apr 2021 18:00
Perhaps I should post this on thw What if section, so my apologies if it is in the wrong section. Initially the Allies wanted to land at high tide, so that the troops have less beach to cross under fire, but as Rommel put millions of obstacles under high tide, they decided that the initial landings would have to be made soon after low tide, to allow demolition groups to blow up enough obstacles to open corridors for the following landing craft. That is why they selected June 5, 6 and 7 as possible D-Days. But when would they have landed, if the germans hadn't put the obstacles and they had wanted to land at high tide? Which days would have met this and their other requirements?
Actually, no, the timing changed after the discovery of the mining of the German seaward obstacle system, but it was never planned for high tide, which would have stranded too many landing craft until the following high tide. It was originally planned for after the turn of the tide and was about an hour later than the actual landings. So the same days would have applied.

The other condition was the moon phase, which limited it to 5, 6, and 7 June.
"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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Re: Date of D-Day if the Allies want to land at high tide

Post by Juan G. C. » 08 Apr 2021 19:05

Richard Anderson wrote:
08 Apr 2021 18:10

Actually, no, the timing changed after the discovery of the mining of the German seaward obstacle system, but it was never planned for high tide, which would have stranded too many landing craft until the following high tide. It was originally planned for after the turn of the tide and was about an hour later than the actual landings. So the same days would have applied.

The other condition was the moon phase, which limited it to 5, 6, and 7 June.
Thanks! Then the obstacles didn't affect the timing?

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

Post by Juan G. C. » 08 Apr 2021 19:15

. It was originally planned for after the turn of the tide and was about an hour later than the actual landings.
Do you mean that originally the landings were going to take place an hour later than when te landings took finally place?

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

Post by Richard Anderson » 09 Apr 2021 00:25

Juan G. C. wrote:
08 Apr 2021 19:15
. It was originally planned for after the turn of the tide and was about an hour later than the actual landings.
Do you mean that originally the landings were going to take place an hour later than when te landings took finally place?
Okay, I went back to review the sequence. Initially, the concept was a landing before dawn, as was done in North Africa, Sicily, and Italy. However, then the feeling shifted to having the landing done with enough light for an observed bombardment of the shore defenses, which, of course, the air force types endorsed. So it was agreed it would be 100 minutes after nautical twilight, thus around 0735. The nice thing about that was it also meant the landing would occur well after the turn of the tide, reducing the beach to be crossed, while not at high tide, which would strand craft until the following high tide. That was what held from about April-May 1943 in discussion at the Assault Training Center, to November-December 1943, when the preliminary operational discussions based on the COSSAC planning began.

That all went out the window when the Germans began extending their obstacle belt from the high-tide line towards the sea. It meant that any landing would need to be seaward of the obstacle belt, so engineers could clear the belt. It could further complicated in February, when the discovery was made the Germans were mining the seaward obstacle belt. As the obstacles got closer and closer to the low-tide line the timing had to shift earlier and earlier so that the obstacles would be exposed enough and there would be enough time to remove or demolish them before the main assault waves came in.

That meant the timing had to be adjusted again, to account for the variable tides along the coast. At UTAH and OMAHA it was 0630, GOLD was at 0720, and JUNO and SWORD was 0735, closest to the initial "ideal" time.
"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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Re: Date of D-Day if the Allies want to land at high tide

Post by Juan G. C. » 09 Apr 2021 07:46

Richard Anderson wrote:
09 Apr 2021 00:25
Juan G. C. wrote:
08 Apr 2021 19:15
. It was originally planned for after the turn of the tide and was about an hour later than the actual landings.
Do you mean that originally the landings were going to take place an hour later than when te landings took finally place?
Okay, I went back to review the sequence. Initially, the concept was a landing before dawn, as was done in North Africa, Sicily, and Italy. However, then the feeling shifted to having the landing done with enough light for an observed bombardment of the shore defenses, which, of course, the air force types endorsed. So it was agreed it would be 100 minutes after nautical twilight, thus around 0735. The nice thing about that was it also meant the landing would occur well after the turn of the tide, reducing the beach to be crossed, while not at high tide, which would strand craft until the following high tide. That was what held from about April-May 1943 in discussion at the Assault Training Center, to November-December 1943, when the preliminary operational discussions based on the COSSAC planning began.

That all went out the window when the Germans began extending their obstacle belt from the high-tide line towards the sea. It meant that any landing would need to be seaward of the obstacle belt, so engineers could clear the belt. It could further complicated in February, when the discovery was made the Germans were mining the seaward obstacle belt. As the obstacles got closer and closer to the low-tide line the timing had to shift earlier and earlier so that the obstacles would be exposed enough and there would be enough time to remove or demolish them before the main assault waves came in.

That meant the timing had to be adjusted again, to account for the variable tides along the coast. At UTAH and OMAHA it was 0630, GOLD was at 0720, and JUNO and SWORD was 0735, closest to the initial "ideal" time.
Thanks! Are the times in British Double Summer Time?

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

Post by Richard Anderson » 09 Apr 2021 15:54

Juan G. C. wrote:
09 Apr 2021 07:46
Thanks! Are the times in British Double Summer Time?
Yes.
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Re: Date of D-Day if the Allies want to land at high tide

Post by Juan G. C. » 09 Apr 2021 18:08

Richard Anderson wrote:
09 Apr 2021 15:54
Yes.
Thanks!

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

Post by OpanaPointer » 09 Apr 2021 19:03

Bad idea. The beach obstacles wouldn't be exposed at high tide. Also the bombers were supposed to bomb the beach and provide instant fox holes. (That didn't work.) At high tide where was comparatively little beach, so the troops would be crowded and bunched. Better productivity from stick grenades and mortar.
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Re: Date of D-Day if the Allies want to land at high tide

Post by Sheldrake » 09 Apr 2021 23:07

OpanaPointer wrote:
09 Apr 2021 19:03
Bad idea. The beach obstacles wouldn't be exposed at high tide. Also the bombers were supposed to bomb the beach and provide instant fox holes. (That didn't work.) At high tide where was comparatively little beach, so the troops would be crowded and bunched. Better productivity from stick grenades and mortar.
Noooooo! The last thing the allied wanted their bombers to do was to create holes on the beach that might drown men and vehicles. No one wanted foxholes on the beach. There was even a bombing test off Brancaster in Norfolk to check that the bombs to be used would NOT create big craters.

I could not find any reference for heavy bombers being set the mission of destroying beach obstacles. It was not a job suited to the capabilities of heavy bombers. Heavy bombers were tasked with hitting the defences above the high water mark, and due to fears about the risks of friendly fire were ordered to bomb 1000 yards inland in the expectation/hope that some bombs would fall short enough to hit the beach defenders.

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

Post by Richard Anderson » 10 Apr 2021 01:12

Sheldrake wrote:
09 Apr 2021 23:07
OpanaPointer wrote:
09 Apr 2021 19:03
Bad idea. The beach obstacles wouldn't be exposed at high tide. Also the bombers were supposed to bomb the beach and provide instant fox holes. (That didn't work.) At high tide where was comparatively little beach, so the troops would be crowded and bunched. Better productivity from stick grenades and mortar.
Noooooo! The last thing the allied wanted their bombers to do was to create holes on the beach that might drown men and vehicles. No one wanted foxholes on the beach. There was even a bombing test off Brancaster in Norfolk to check that the bombs to be used would NOT create big craters.

I could not find any reference for heavy bombers being set the mission of destroying beach obstacles. It was not a job suited to the capabilities of heavy bombers. Heavy bombers were tasked with hitting the defences above the high water mark, and due to fears about the risks of friendly fire were ordered to bomb 1000 yards inland in the expectation/hope that some bombs would fall short enough to hit the beach defenders.
Agreed. This is actually one of the more mysterious aspects of D-Day and apparently only was a factor on OMAHA. Somehow the idea got around to the troops that the intent of the heavy bomber mission was to crater the beach to create foxholes for them so they could leapfrog forward with so protection.

There is nothing, Zero, Zip, Nada, in any of the planning, by V Corps or by the USAAF that mentions such an idea.

The bombing was intended to help clear the obstacle belt above the high tide line and keep the defenders heads down.
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Re: Date of D-Day if the Allies want to land at high tide

Post by Carl Schwamberger » 10 Apr 2021 04:38

Sheldrake wrote:
09 Apr 2021 23:07
Noooooo! The last thing the allied wanted their bombers to do was to create holes on the beach that might drown men and vehicles. No one wanted foxholes on the beach. There was even a bombing test off Brancaster in Norfolk to check that the bombs to be used would NOT create big craters.

Seen it repeatedly mentioned US 1st Army staff were concerned about larger bombs badly cratering the beach exits, thus creating dense obstacles to moving off the beach. This leads to descriptions of the 8th AF bomb load as being predominantly 250lb bombs with a small portion of 500+ lb bombs. A bit of inspection of ammunition effects tables 'strongly suggests' a bomb mix like that would be deficient in removing the obstacle of the defenders.
Sheldrake wrote:
09 Apr 2021 23:07
I could not find any reference for heavy bombers being set the mission of destroying beach obstacles. It was not a job suited to the capabilities of heavy bombers. Heavy bombers were tasked with hitting the defences above the high water mark, and due to fears about the risks of friendly fire were ordered to bomb 1000 yards inland in the expectation/hope that some bombs would fall short enough to hit the beach defenders.
That aint gonna work.

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

Post by Sheldrake » 10 Apr 2021 09:42

Carl Schwamberger wrote:
10 Apr 2021 04:38
Sheldrake wrote:
09 Apr 2021 23:07
Noooooo! The last thing the allied wanted their bombers to do was to create holes on the beach that might drown men and vehicles. No one wanted foxholes on the beach. There was even a bombing test off Brancaster in Norfolk to check that the bombs to be used would NOT create big craters.

Seen it repeatedly mentioned US 1st Army staff were concerned about larger bombs badly cratering the beach exits, thus creating dense obstacles to moving off the beach. This leads to descriptions of the 8th AF bomb load as being predominantly 250lb bombs with a small portion of 500+ lb bombs. A bit of inspection of ammunition effects tables 'strongly suggests' a bomb mix like that would be deficient in removing the obstacle of the defenders.
Sheldrake wrote:
09 Apr 2021 23:07
I could not find any reference for heavy bombers being set the mission of destroying beach obstacles. It was not a job suited to the capabilities of heavy bombers. Heavy bombers were tasked with hitting the defences above the high water mark, and due to fears about the risks of friendly fire were ordered to bomb 1000 yards inland in the expectation/hope that some bombs would fall short enough to hit the beach defenders.
That aint gonna work.
Well thats what they did. There was an assumption that the US Day bombers were so inaccurate that given a tendency for creep back around 10% of the bombs might fall 1000 yards short and thus on the target.

By and large the USAAF day bombers have a not wholly undeserved reputation for bombing friend and foe indiscriminately. However on D Day they seem to have bombed where they were told to. I have plotted where, as far as possible the evidence of bombing against the targets in the fireplan. In the British sector at least the bombs fell with an MPI 1000 yards inland. Bad news for the Mont Fleury Battery 1000 yards inland from Gold Beach where the craters are visible on the aerial photos. Bad news too for the British paras making their way into the perimeter 1000 yards inland from Franceville-Plage defensive position.

My current view of the D day fire plan is that the impressive fireplan had only a limited effect neutralising the beach defenders. There was such a fear of friendly fire casualties that safety margins were far far too generous in time and space, allowing the defenders to recover. Not unlike the first day of the Somme.

However, the bombing and naval gunfire did neutralise much of the German artillery support. Only on Omaha Beach were the undetected guns of 352 division were able to fire without reply. None of the coastal batteries were able to engage the vulnerable transports. Bombing does seem to ave knocked out the wire communications within e.g. Longiues sur Mer and between OPs and guns in the 716 Div sector

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

Post by rcocean » 10 Apr 2021 15:26

It retrospect, it would've been better to have delayed he Omaha landing even longer and allow the Navy to pound the beaches. I think this was the point that a British author made in "Omaha Beach - A Flawed Victory". Either land in darkness so the Germans don't have a good target, or blast the beach defenses with enough Naval Support to allow the troops an easy landing. He blames Bradley for choosing an in-between "worst of all worlds" choice, namely a landing in day light with inadequate naval gun support. One wonders how much the British benefited from extra time for their ships to pound the beaches.

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

Post by Carl Schwamberger » 10 Apr 2021 15:58

Sheldrake wrote:
10 Apr 2021 09:42
Carl Schwamberger wrote:
10 Apr 2021 04:38
Sheldrake wrote:
09 Apr 2021 23:07
Noooooo! The last thing the allied wanted their bombers to do was to create holes on the beach that might drown men and vehicles. No one wanted foxholes on the beach. There was even a bombing test off Brancaster in Norfolk to check that the bombs to be used would NOT create big craters.

Seen it repeatedly mentioned US 1st Army staff were concerned about larger bombs badly cratering the beach exits, thus creating dense obstacles to moving off the beach. This leads to descriptions of the 8th AF bomb load as being predominantly 250lb bombs with a small portion of 500+ lb bombs. A bit of inspection of ammunition effects tables 'strongly suggests' a bomb mix like that would be deficient in removing the obstacle of the defenders.
Sheldrake wrote:
09 Apr 2021 23:07
I could not find any reference for heavy bombers being set the mission of destroying beach obstacles. It was not a job suited to the capabilities of heavy bombers. Heavy bombers were tasked with hitting the defences above the high water mark, and due to fears about the risks of friendly fire were ordered to bomb 1000 yards inland in the expectation/hope that some bombs would fall short enough to hit the beach defenders.
That aint gonna work.
Well thats what they did. There was an assumption that the US Day bombers were so inaccurate that given a tendency for creep back around 10% of the bombs might fall 1000 yards short and thus on the target.
If you are thinking this way WTF is the point of ordering the mission at all? Ive read both Bradleys and Dolittles versions of the planning for this, and the op COBRA air air bombardment. They lack fine detail, but it appears they were talking past each other, neither really grasping what the other was saying.
Sheldrake wrote:
09 Apr 2021 23:07
My current view of the D day fire plan is that the impressive fireplan had only a limited effect neutralising the beach defenders.
Yeah, the leading assault waves would agree with you. One Brit in a early wave thought it notable that a AT gun had been neutralized. UTAH Beach looks like the only one where the massed air bombardment had the desired effect on at least one WN. The circumstances there are very different from those of OMAHA Beach, or presumably the other beaches.

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