Early May Overlord

[Carl Schwamberger]

Technically perhaps. But Roosevelt tended to stay out of the details once he set general policy. He liked to follow events & be informed but his management style leaned heavily on letting his subordinates do their job.

Had Roosevelt believed it necessary for Overlord to take place in early May (e. g. If he believed he had to reassure the Russians because otherwise they would make a separate peace), could he have vetoed the postponement?

Technically yes. He overrode Marshals advice/position at the SYMBOL conference Jan 1943. Agreeing with Churchill to delay invasion of NW France until 1944. Not a good example, but I can't think of any others. Roosevelt generally understood the essential factors in major operations. He was a good listener, did his research, and had fourteen odd years as a military chief as Asst Sec Nav & Pressident.

Also Roosevelt knew the Politburo/Stalin had passed their 'peace moment' and were determined to do as much damage to Germany with or without Allied help. So Russian peace moves is far out on a speculative limb. I'd not go there without a lot of education on the internal politics of the Politburo & senior Red Army leadership. & I don't have that.

[JKernwerk]

... Much of May was occupied in getting the massive number of craft up to at least a 95% operational readiness rate. They actually managed to exceed it, but it was an all hands on deck exercise that was complicated by worries about possible British dockyard strikes affecting it.

A Royal Marine related to me his experience. He was part of a RM group redesigned as boat crews in the spring of 1944. Reporting for training he observed "hundreds" of landing craft docked and anchored in the Thames estuary without crews. His impression was the boats were not entirely crewed and ready until late May. His naval career was ended later in the summer when the RM crews turned the boats over to Navy personnel and were redistributed into the Commando groups.

Could it be that these boats where part of the camouflage campaign to make the Germans think they were to attack at the Pas de Calais?
If so they had only to do with "Overlord" as just being there and not to be intended to use for real.
I do not know where the boats came to shore from America but why store them in the Thames and then use boarding harbours in the South of England.
When you want to move these boats in the Thames through the strait of Dover before they were able to use these the Germans would have a nice clue because the whole strait is observable from France.
Many guns could cover the whole strait and could (easily?) aim the slow fleet of crafts.
JK

From mid-1943 to mid-1944 large numbers or Royal Marines (Wiki says 500 officers and 12500 men) were reallocated to man landing craft in time for D-Day. These came from breaking up the Mobile Naval Base Organisation and other shore units and from the RM detachments on ships that returned from the Far East in late 1943 to be laid up e.g. the R class battleships Revenge, Resolution and Royal Sovereign and various D class cruisers.

The RN took on 13 Empire class LSI(L) between Oct 1943 and Jan 1944 each of which had to be fitted out with 18 LCA and 1 LCM which were built in the UK. All took part in the D-Day landings. Crews had to be found for those 247 small landing craft and many came from newly formed RM manned landing craft flotillas. Add to that all the ships that were temporarily fitted out as LSI for the Normandy invasion which also needed LCAs. Like the tanks and other vehicles stored in vehicle parks across the south of the country those small landing craft had to be stored somewhere pending their crews being trained and allocated as they weren't all built in the last few months before D-Day. Unlike larger vessels, LCA/LCM crews did not live aboard their craft for more than a few days at a time. The facilities to care for them aboard just did not exist. So the story is entirely believable. You will find photos here of a batch being handed over to the RN on the Thames at Reading in Sept 1944.
https://www.combinedops.com/NEW%20LANDING%20CRAFT.htm

Such was the manpower shortage in late 1944 that many of these RM boat crew were then remustered to form 2 RM infantry brigades for service in NWE.

Clear explanation, but how were these craft moved to the South coast of england, by truck or smaller waterways?
K

[Carl Schwamberger]

Must have been hard worked - they were discharging over 5,000 tons daily in March.

DUKW were heavily used at Anzio instead to discharge from shipping to shore. About 450-490 were used.

The DUKW were heavily used at Normady, & had a lot to do with both UTAH and OMAHA beaches reaching or exceeding their planned discharge. The technique with the DUKW was to come alongside the cargo ship, send up a empty cargo net. Another ready loaded cargo net with approx a ton of material, boxes of rations, fuel cans, ammunition crates, whatever, would be lowered into the DUKW which then went ashore. The Beach Master directed the vehicle to the appropriate depot inland, where crane unloaded the cargo net and dropped a empty in. Repeat as needed a DUKW could deliver a ton ashore in 1-2 hours. Leaving time for crew rest & vehicle maintenance 12 hours of deliveries per day is very possible. Thats between 6 & 12 tons prepay for vehicle. I suspect the actual was higher, but using a average of 9 tons daily 100 DUKW would bring ashore 900 tons.daily, 500 sorties equals 4500 tons daily, or 135,000 tons of loose small bulk cargo monthly cargo monthly.

[Carl Schwamberger]

... Much of May was occupied in getting the massive number of craft up to at least a 95% operational readiness rate. They actually managed to exceed it, but it was an all hands on deck exercise that was complicated by worries about possible British dockyard strikes affecting it.

A Royal Marine related to me his experience. He was part of a RM group redesigned as boat crews in the spring of 1944. Reporting for training he observed "hundreds" of landing craft docked and anchored in the Thames estuary without crews. His impression was the boats were not entirely crewed and ready until late May. His naval career was ended later in the summer when the RM crews turned the boats over to Navy personnel and were redistributed into the Commando groups.

Could it be that these boats where part of the camouflage campaign to make the Germans think they were to attack at the Pas de Calais?

Possibly a secondary motive.

If so they had only to do with "Overlord" as just being there and not to be intended to use for real.
I do not know where the boats came to shore from America but why store them in the Thames and then use boarding harbours in the South of England.

My RM correspondent related they left no boats behind that he could see. & they loaded & departed from the Thames region. From other sources the amphibious 'Force L' departed from the Thames serially the 4th though 7th and carried a large portion of the imeadiate follow up echelons landing after the assault on the 7th & 8th. Most of the first 48 hours follow up was preloaded by 4 June. This is similar to the follow on force for the US Army, which embarked its combat elements in the Bristol Channel ports. Some elements were stationed at Liverpool, and as far North as Ireland.

This map shows the nominal routes of the naval force to the landing sites. These were altered some by the storm and delay of the 5th June. Groups with the vulnerable ships were ordered into harbors and sheltered areas changing the actual courses followed.

[Sheldrake]

My RM correspondent related they left no boats behind that he could see. & they loaded & departed from the Thames region. From other sources the amphibious 'Force L' departed from the Thames serially the 4th though 7th and carried a large portion of the imeadiate follow up echelons landing after the assault on the 7th & 8th. Most of the first 48 hours follow up was preloaded by 4 June. This is similar to the follow on force for the US Army, which embarked its combat elements in the Bristol Channel ports. Some elements were stationed at Liverpool, and as far North as Ireland.

This map shows the nominal routes of the naval force to the landing sites. These were altered some by the storm and delay of the 5th June. Groups with the vulnerable ships were ordered into harbors and sheltered areas changing the actual courses followed.
Op Neptune Routes.png

I think Force L included 7th Armoured, 49th and 51st Infantry Divisions.

[Carl Schwamberger]

Yes they were. Following ashore On the 7th & 8th, similar to the US 2d & 90th ID. Im unsure if the 7th & 27th Amd Bde landing on 6th June were affiliated with the 7th Armored Div or independent Bde

[EwenS]

The 13/18th Hussars with DD tanks in the independent 27th Armoured Brigade landed early on 6th June on Sword beach. The non DD elements of that Regt and the other regiments in the Brigade followed later that day.

4th County of London Yeomanry, part of 22nd Armoured Brigade in 7th Armoured Division came ashore as part of the follow up on the evening of 6th June on Gold beach. The rest of the division followed over the next week.

Details of 7th AD build up and landing here
http://www.desertrats.org.uk/battles1944.htm#England

[Carl Schwamberger]

Thanks. Sounds like the units of the US follow up. A complex mix of priorities and transport capability. I used to be paid to do amphibious war stuff & just loading a LST fast & efficiently is not a task for the amateur.

[Carl Schwamberger]

...
Clear explanation, but how were these craft moved to the South coast of england, by truck or smaller waterways?
K

The smaller boats embarked on the larger amphib transport ships in the Thames area, the larger embarked their cargos, soldiers & vehicles, whatever. They all followed the same route out of the Thames and around to the Channel. The ports on the S coast were overtaxed. I've heard close to half the preloaded men and material landing to D+3 were embarked in ports other than the Channel ports. The Thames region, ports on the Bristol Channel, Liverpool, some as far north as N Ireland.