Source: Historical Section, COMNAVEU. "Administrative History of U.S. Naval Forces in Europe, 1940-1946." vol. 5. (London, 1946): 301-337 [This manuscript, identified as United States Naval Administrative History of World War II #147-E, is located in the Navy Department Library's Rare Book Room.]

PART II
DESIGNATION AND POSTPONEMENT OF D-DAY

A. 5 June Designated as D-Day.

29. With the approach of the invasion target date (May 31), a definite decision on D-day and H-hour, was required. No single question had been discussed more often. Until obstructions were discovered on the beaches, the number of days when an acceptable combination of tidal and light conditions would obtain was not severely limited. Confirmation of the existence of such beach obstacles required a re-examination of the question of the timing of the initial assault. At a Meeting held at Supreme Headquarters on 1 May, the situation created by the extension of obstacles was discussed. It was decided that they must be dealt with dry shod in. areas in which they stood in less than two feet if water.¹ This necessitated the adjustment of H-hour, which in turn required the fixing of a target date for D-day. After some days' consideration, Admiral Ramsay decided:

    1. That five different H-hours would have to be accepted, one for each assault force;

    2. That the earliest acceptable dates for the assault from the Naval point of view, were the 5th and 7th June, and,

    3. That the 7th June could be accepted in case of extreme necessity. General Eisenhower was informed of these conclusions at a meeting on 8 May.

30. The Supreme Commander, on 23 May, signaled his decision in special code that D-day was provisionally fixed for 5 June,² At 2330, 25 May, all holders of ON's were

directed to open their operation orders and to "execute operation NEPTUNE". Contrary to original intentions the nomination of D-day and H-hour was withheld in order to avoid announcing the newly decided five differing H-hours until after the orders had been read and understood. Three days later, at 1800 on 28 May ANCXF signalled that D-day was fixed for the 5th and that H-hour for respective assault forces would be:

Force 0	0610
Force U	0600
Forces S and G	0645
Force J, right sector	0655
Force J, left sector1	0705

B. NEPTUNE Forces in Movement

31. The naming of D-day and H-hour, with the previous order to "carry out Operation NEPTUNE" was the executive signal which started all the intricate action and movements detailed in ON's. It was intended that no further despatch would be sent unless weather conditions forced a postponement of D-day. As the days went by it became increasingly clear that the long spell of fine weather was showing signs of breaking up, and that an unsettled spell was impending. On 29 May, at a meeting at which the Deputy Supreme Commander (Air Chief Marshall Tedder) was present, it was decided that Commanders Meetings to give critical examination to weather forecasts should be held at ANCXF Battle Headquarters twice daily from D minus 3 (2nd June) onwards. Details of movements of forces, in the event of postponement of D-day were promulgated, as 31 May, amplifying those contained in the ON's.

32. The first convoys to sail with destinations in the Assault area left Oban, Scotland, south bound between 0700 and 1030 on the morning of 31 May. These convoys consisted of 54 CORNCOBS (Block ships to be sunk off the beaches on D plus l to form breakwaters). They sailed with sealed orders and under the impression that they were going only to their "southerly anchorages". Concurrently the intricate business of loading and, final assembly of

assault forces was proceeding according to plan. The congestion of all the ports necessitated very careful timing and movement of craft, both loaded and unloaded.¹ The job of loading and assembly had been well practised and few hitches developed. The overloading of craft continued, despite restrictive orders to prevent it, and some time was lost backing unwieldy vehicles onto the landing vessels. But "the knowledge that they were really "off at last" acted as a great incentive"² to all hands, and the armada was loaded and assembled in good time. During this most vulnerable period the enemy made no effort whatever to interfere.
33. At 1200, 1st June 1944, Admiral Sir Bertram Ramsay assumed operational command of "NEPTUNE" Forces and general control of operations in the Channel.

C. Weather Intervenes: Postponement of Assault

34. The Supreme Commander's chief concern after June 1 was the weather dilemma. He presided over the first meeting of the Commanders-In-Chief to consider the weather forecast at ANCXF Headquarters on the morning of 2 June. Less favorable conditions were predicted for June 5th, particularly as regards cloud and cloud base, which was of special concern to the Air Force, since it would affect the passage of the Airborne divisions.

35. The first warships to sail for the Assault Area (Bombarding Force D) weighed anchor from the Clyde in the evening (2nd June). The tyro midget submarines X23 and

X.20,¹ sailed from Portsmouth. H.M.S. Nelson left Scapa for Milford Haven.
36. The weather further deteriorated over night. June 3rd was cloudy, with a westerly wind force 3 to 4 backing to S.W. and increasing to force 5. The sea was slight, increasing to moderate, and the cloud base was lowering. Commanders' meetings were held at 0430 and again at 2130 to consider the weather forecast. Further deterioration was predicted for 8th June. Though the wind was expected to increase to force 5 Admiral Ramsay considered that the Navy would be able to undertake its task if reasonable protection could be given from the air. Since the conditions predicted affected the airborne and Air Force plans more unfavorably than the Naval plan, the Supreme Commander decided at the evening meeting to await a possible change in the forecast in the next six hours. Meanwhile the ships continued to put to sea according to schedule. W.T.F. Bombarding Forces sailed from Belfast and the balance of the E.T.F., Bombarding Forces from the Clyde. Late in the afternoon, the little craft of Force U, the first of the Assault Force convoys, put to sea from Dartmouth, Salcombe and Brixham.

37. The Supreme Commander again met with his three Commanders-in-Chief, at 0415, 4th June, to consider the weather. The sky was overcast, with the cloud ceiling low, with a wind of force 6 from the south west. The sea was moderate but rain was falling. The forecast for the 8th was for an increase of wind and a further deterioration in cloud conditions. Admiralty promulgated a gale warning for the Irish Sea (wind force 8). The Supreme Commander reluctantly decided to postpone the operation for one day. A general signal ordering the postponement was promulgated from ANCXF Headquarters at 0515.²

38. Convoys at sea were ordered to reverse their courses, and to proceed to sheltering anchorages. Those which had not yet sailed were retained in harbor. The CORNCOB

convoys were diverted to Poole Bay. The Bombarding Forces reversed course with the intention of remaining at sea. Movements generally went in accordance with the postponement plan, and at 2250 that evening (4th June), the Commander-in-Chief, Portsmouth, reported all NEPTUNE convoys anchored, except Group U.2.A., still under way off Portland where the harbor was too crowded to permit entry.
39. Group U.2.A. was a very large convoy totaling 138 vessels (77 British LCT, 61 U.S. LCT, 4 escorts and one rescue tug). It had progressed some distance ahead of its planned position and apparently did not receive the postponement signal. At 0900 it was 25 miles to the southward of St. Catherines Point and still driving south. Rear-Admiral Moon sent two destroyers to turn the convoy back, and the Commander-in-Chief, Portsmouth, sent a Walrus aircraft. By 0948 all the craft had turned to the northward.¹ They were ordered to anchor in Weymouth Bay and refuel. Great difficulty was experienced in proceeding westward against the wind, which was then blowing W.S.W. force 5 to 6, with a short steep sea on the port bow. It was after midnight before any of the craft were anchored in the Bay.

40. The two midget submarines, assigned to mark off the assault beaches, reached their positions at about the time that the decision to postpone the operation was taken, when they received the postponement signal, they submerged according to plan and remained on position for 48 hours until the arrival of the forces on June 6th.

D. The Supreme Commander's Dilemma: 6 June Fixed As D-Day

41. The Supreme Commander held another meeting with: his C-in-C at 2115 on Sunday 4th of June. The existing weather conditions were bad, typical of December rather than of June. The meteorological officers believed that there was a good prospect that the weather would improve

for 12 hours or so during the morning of the 6th of June. The conditions predicted for those hours were:- wind W.S.W., force 5, backing and decreasing slightly but freshening again in the afternoon of the 6th; the weather fair with showers and an overcast developing on the 6th; visibility mainly good; waves six feet in open sea decreasing slowly; outlook unsettled, with westerly weather and further deterioration continuing.
42. General Eisenhower, after full consideration of all factors, decided to proceed with the operation on 6 June. There was a prospect of poor but possible water on that day. The weather prospect for the 7th and 8th was worse than that for the 6th. Two weeks postponement would be necessary until the next suitable tidal-daybreak combination if the invasion was not launched on the 6th or 7th.¹ Confirmation that D-day was 6th June was therefore signalled to all forces.

43. On the new schedule, H-hour for the 5 forces were to be:

    Force U	0630
    Force O	0630
    Forces G and S	0725
    Force J, right sector	0735
    Force J, left sector	0745

44. Admiral Ramsay summarized the situation, on this evening of June the 4th, as follows:

    "On this day, the preparatory period of Operation NFPTUNE, may be considered concluded, with the following brief picture of the situation:-

    1. Naval and Military assault and invasion forces had been assembled with all material that could be male available.

2. Naval orders had been promulgated to the utmost foreseeable detail, and plans completed, with the exception of certain details concerned with Air Force intentions, which had to be signalled to ships and craft after they had sailed for the assault.

3. Assault ships and craft were loading, or preparing to load, at every available berth where facilities existed from the Thames around the South Coast to the Bristol Channel. A broad dividing line between the Allied forces was at Poole; U.S. ships and personnel of Force O and U were being loaded in ports to the west of Poole while British ships and personnel were loading in that port and to the eastward. The assembly of the bombarding forces was complete.

4. No serious interference with preparations had been effected by the enemy.

5. Air Force Authorities had reported successful attacks on the targets (especially enemy Radar Stations) of naval interest specified by ANCXF and these attacks were continuing.

6. The enemy was aware (though imperfectly) that this unparalleled assembly of shipping was approaching its climax, and that the state of preparations for the projected invasion had reached an advanced stage.

7. No particular sign was discernible that the enemy had knowledge of the point of attack selected, but since February their defences in the Bay of the Seine had gradually been strengthened in common with all other parts of the coast where assault was practicable.

8. Major difficulties which had arisen during the planning and mounting of the project can be attributed, in nearly every case, to the magnitude of the operation, creating strained resources in man-power, material and supplies.

9. Problems of concern still remained in weather prospects, shortage of tugs, integration with

Air force plans when finalised, and strain on communications. There were also additional problems in connection with MULBERRIES, through the failure of Army authorities to deliver tows and stores for WHALES and adequate pumping gear for PHOENIX units, on which naval salvage gear had to be utilised.
10. Chief problem of all however, as the specified D-day approached was weather and the chances that suitable conditions for the assault would exist on 6th June. A long spell of fine weather had continued through May, but now the Meteorological Officers found with dismay that the fine spell showed signs of giving way to more unsettled conditions. From 1st June onwards any study of the weather chart could only result in grave concern both as to the prospects ahead and as to the difficulties of accurate forecast.

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Footnotes:

p.392 #1 A number of reconnaissance landings, arranged by the Chief of Combined Operations, were carried out to investigate the extent of these obstacles. On the night of 17/18th May, two officers failed to return from one of these missions in the Pas de Calais area.

p.392 #2 As sailing orders to certain units, such as the CORNCOBS (Blockships) at Oban, had to issued as early as D minus 8, it was necessary to fix D-day provisionally as early as possible.

p.393 #1 The basic H-hour for purpose of sailing and general timing was in the ETF 0654, in the WTF 0610.

p.394 #1 In his report C-in-C Portsmouth stated:
"It is a commonplace expression to say that an anchorage is 'full of ships', but in the case of the East and West Solent with an available area of approximately 22 square miles in which to anchor ships, it was literally true. On 18th May the Admiralty offered the Commander-in-Chief, Portsmouth, the services of H.M.S. TYNE, but it was only possible to accept her because H.M.S. WARSPITE was not being sent to Portsmouth till D-day, which gave one berth in hand". - Report on Operation "OVERLORD".

p.394 #2 Report of NC Force S contained ANCXF Report Vol.II Paragraphs 8 and 9.

p.395 #1 X23 and X20 were towed by H.M. Trawlers Sapper and Darthema till in Lat. 50°22'N Long. 0°50'W, when they were slipped at about 0430, 3rd June. They proceeded under their own power, dived throughout daylight, 3rd June, surfacing after dark to cross the enemy mine barrier, and arrived off the French coast about 0500, 4th June.

p.395 #2 This signal included the revised times of H-hours for 8th June.

p.396 #1 About half an hour later, the 14th Minesweeping flotilla reported mines in approximately lat. 50°15'N., long. 1°16'W, (15 miles south of St. Catherines point). This area was in the route of the Force U convoys. Five mines were cut and two exploded in the sweep - all of the New German X star type.

p.397 #1 In his Report, Admiral Ramsay said that although the unfavorable weather caused difficulties and damage to craft off the beaches later, the advantages gained by surprise were so striking that the decision of the Supreme Commander to go on despite the weather was amply justified. "A postponement of one more day, e.g., till 7th June would, in the event, have proved disastrous owing to the conditions of sea off the beaches. The problems arising out of a postponement of 12 or 14 days to the next suitable period are too appalling even to contemplate." ANCXF Report Vol. 1 Page 10. The great and utterly unexpected and unpredicted storm broke on what would have been the afternoon of D-day.