WEATHER CONTROLLED D-DAY PLANS

Normally, the posts in the 1944 Series “Liberating The World” are for paid subscribers, my way of saying thanks for their support. However, the D-Day posts this week - in which we celebrate the 80th anniversary of the greatest invasion in history, which are likely the last celebration where anyone who was there in1944 will be in attendance - are with this post sent to all subscribers. I hope some of the free subscribers will consider joining the paid subscribers to be able to enjoy the entire series that is avaiable to paid subscribers.

The weather nearly ended the invasion, forcing a one-day delay, and the breaking loose with heavy storms the day after the troops got ashore.

This year, I have been publishing a series, “1944: liberating the world” for the paid subscribers. The D-Day postss this week will go to everyone, in hopes some of you will decide you’d like to access the entire series by joining the paid subscribers.

This is excerpted from “When the Sea Came Alive: An Oral History of D-Day,” by Garrett M. Graff, a historian who writes from first person interviews and memoirs.

Why D-Day nearly didn’t happen

After years of planning and billions in spending, D-Day came down to a single factor beyond the Allies’ control: the weather. Operation Overlord involved 1 million combatants moving together across the English Channel to pierce Hitler’s Fortress Europe. The five-division, five-beach invasion plan wasn’t as large as Eisenhower wanted, but it was the largest the Allies could move across the channel. The Normandy beaches weren’t the easiest to attack, but they were the best available.

In the early days of June 1944, Eisenhower confronted his most consequential question: Would the weather be decent enough for the invasion to proceed? The planners at the Supreme Headquarters Allied Expeditionary Force (SHAEF) had calculated that there were only three days in early June when the moons and the tides aligned favorably for the massive armada and paratrooper drop that would carry out Overlord’s opening stages. If the weather didn’t cooperate during that window, the invasion would have to be pushed back two to four weeks — a setback that might compromise its secrecy and call into question whether the Allies would have enough time to push forward their campaign against the Third Reich before winter.

As June began and the first invasion ships were putting to sea, the Allied commanders decamped for Portsmouth on England’s southern coast and daily meetings at the British naval headquarters at Southwick House, where they’d make the final decision on whether to proceed.

This narrative is based on dozens of archival sources, including oral histories, memoirs, official reports, news articles and contemporaneous letters.

Maj. John Dalgleish, planning staff, Royal Army Service Corps: June arrived. The blossoms were full. The birds trilled their songs in the woodland around the offices.

Capt. J.M. Stagg, chief meteorologist, SHAEF: Southwick House is a spacious mansion set in extensive wooded grounds, surrounded by gardens, lawns and avenues. It lies just north of Portsmouth in the shadow of Ports Down ridge from which there is a panoramic view of the city and its harbors and anchorages. The whole water surface was so crowded with craft of every size and description — battleships, destroyers, transport vessels and hundreds of landing craft, all lying rail to rail — that it seemed it would be impossible to get them out quickly in an orderly fashion. It was a most impressive sight.

Capt. Kay Summersby, British Mechanized Transport Corps, aide and secretary to Eisenhower, SHAEF: Nerve-ends were so exposed, security so exacting, that even the Supreme Allied Commander had to carry a pass. Everyone topside was jumpy over our Other Enemy: the weather. The area was alive with weather experts, meteorologists and plain second-guessers — all studying, figuring, worrying about the weather.

Gen. Dwight D. Eisenhower, Supreme Allied Commander, SHAEF: If none of the days should prove satisfactory from the standpoint of weather, consequences would ensue that were almost terrifying to contemplate. Secrecy would be lost. Assault troops would be unloaded and crowded back into assembly areas enclosed in barbed wire, where their original places would already have been taken by those to follow in subsequent waves. A wait of at least 14 days, possibly 28, would be necessary — a sort of suspended animation involving more than 2 million men!

Lt. Gen. Walter Bedell “Beetle” Smith, chief of staff, SHAEF: June dawned dark and stormy with a gale over the channel. Up at SHIPMATE — the code name of the Advanced Command Post on the bluff — we shivered in our tents and trailers.

Eisenhower: We met with the meteorologic committee twice daily, once at 9:30 in the evening and once at 4:00 in the morning.

Smith: We knew the channel could be an implacable enemy, capable of delivering us as disastrous a blow afloat as we should encounter from the German guns when we rushed the beaches.

To predict the weather they’d face, the Allies relied on a trio of two-man meteorological teams based at three weather centers — the U.K. Meteorological Office in Dunstable; the U.S. Army Eighth Air Force headquarters, known as Widewing; and the Royal Navy’s headquarters in Portsmouth, referred to as the Admiralty. Drawing on hundreds of reports from across the British Isles, the United States, the North Atlantic and Europe, each team approached its forecasts in its own way, with its own methodology — and the three teams agreed only rarely.

Lt. Cmdr. Lawrence Hogben, meteorologist, Royal New Zealand Navy, Admiralty headquarters: We used data garnered from special weather recce [reconnaissance] flights, ship observations, U.K. weather sites and pinched what we could from the Germans — once we broke their weather codes — and redrew our charts every few hours.

Capt. Harry C. Butcher, naval aide to Eisenhower, SHAEF: I lunched with Brig. Gen. Arthur S. Nevins, and we joked about the term “agreed weather report,” which comes from the variety of air, naval and ground weathermen. He said that Group Captain Stagg, who is chairman of the committee of experts, has telephone conferences via scrambler with all the prophets each morning. He said at the outset of the conversation it would seem that all are talking about a different subject, but eventually the weathermen agree on the weather, at least as to what they will predict.

Hogben: None of us were operating with any of the technology and equipment that our successors today take for granted, such as satellites, weather radar, computer modeling and instant communications, and predicting conditions more than a day or two in advance was hazardous.

Sverre Petterssen, meteorologist, Norwegian Air Force, U.K. Meteorological Office: From the very beginning of weather forecasting — about 1855 — until about 1965, when versatile electronic computers began to make their influence felt, simple extrapolation of the movement and rate of development of weather systems remained an important technique. However, the usefulness of this method is limited largely to forecasts for short periods, say, up to 36 or, at most, 48 hours.

Preliminary forecasts for the invasion period were ominous — potentially historically bad. The channel was experiencing storms strong enough to devastate the invasion fleet long before it arrived in France.

Stagg: The whole north Atlantic Ocean area appeared to be filled with a succession of depressions, any one of which could blow into violence. In all the charts for the 40 or 50 years I had examined, I could not recall one which at this time of year remotely resembled this chart in the number and intensity of depressions it portrayed at one time.

Hogben: All we knew was there were several storms blowing across the Atlantic toward us, any one of which would have whipped up the waters where the fleet was gathering.

Stagg: I do recall the earlier part of that day as the nadir of strain and despondency. When I took leave of Gen. [Freddie] Morgan [the allied deputy chief of staff and lead Overlord planner] before coming away from the main headquarters to join the advance party at Portsmouth, he had said, “Good luck, Stagg; may all your depressions be nice little ones: but remember, we’ll string you up from the nearest lamp post if you don’t read the omens aright.”

Petterssen: I felt we stood face to face with a crisis.

Smith: By 1000 hours on June 3, it was evident that the weather was worsening, not improving.

Even as the troops boarded their ships that Saturday, June 3, the hours ticked by with little improvement in the forecast.

Stagg: I said, “Gentlemen, the fears my colleagues and I had yesterday about the weather for the next three or four days have been confirmed. The whole weather set-up over the British Isles and, even more so, to the west over the northeast Atlantic is very disturbed and complex.”

Gen. Bernard Law Montgomery, commander of Allied ground forces (21st Army Group): We decided to make no changes. But we knew that a final decision regarding postponement must be taken early on June 4, and even then some of the convoys would have sailed.

Stagg: Throughout this recital, Gen. Eisenhower sat motionless, with his head slightly to one side resting on his hand, staring steadily toward me. All in the room seemed to be temporarily stunned: The gloom attributed to me last night had now fallen on everyone. Adm. [Bertram] Ramsay broke the grave silence: “Are the force-5 winds along the channel to continue on Monday and Tuesday?”

“Yes, sir.”

“And the cloud on those days?”

“As the situation is at this moment I could not attempt to differentiate one day from another in regard to cloudiness through the whole period from tomorrow till Wednesday when we expect the clearing front to pass through.”

When he came out, Gen. [Harold] Bull told us: “The Supreme Commander has made a provisional decision to hold up the operation on a day-to-day basis. Some of the forces will still sail tonight, but Gen. Eisenhower and his commanders will meet again at 4:15 a.m. tomorrow morning to hear what you have to say. They will then decide definitely whether the first assaults will be postponed from Monday to Tuesday.”

As I came out of Southwick House about midnight, Air Chief Marshal [Arthur] Tedder passed, lighting his pipe. He turned to me and, smiling, said, “Pleasant dreams, Stagg.” He knew that there could not even be sleep. Through the trees, we could see that the sky was almost clear and everything around was still and quiet.

Summersby: June 4 — supposed to be D-Day — undoubtedly was the longest day of 1944.

Maj. Gen. Francis “Freddie” de Guingand, chief of staff to Gen. Montgomery: At 4.30 a.m., June 4th, the same scene again. The same room. The coffee. The men feeling grey and a little unsteady. The meteorologists came in, and it was seen at once that they had no better news.

Stagg: Gen. Eisenhower said, “In that case, gentlemen, it looks to me as if we must confirm the provisional decision we took at the last meeting. Compared with the enemy’s forces, ours are not overwhelmingly strong: We need every help our air superiority can give us. If the air cannot operate we must postpone. Are there any dissentient voices?” There were none. “We must call off the sailing of the last forces and take steps to recall the forces that have already sailed.” Gen. Eisenhower instructed his chief of staff to inform the Combined Chiefs of Staff that the assault had been postponed by one day.

De Guingand: It was an immense undertaking to postpone D-Day. The troops and tanks and guns were embarked and waiting at scores of secret ports around the coast of England. The bombers were waiting on the airfields. The whole elaborate machine was poised to move on this day. And to upset it now, to let some ships put to sea and then bring them back, to retard the immense and exact program of the build-up, to alter the schedule of the trains and the convoys and the loading, to keep the waiting million of men strung at high tension — all this was a fearfully dangerous prospect. Worse still, the meteorologists warned the meeting that if these next few days were lost in inaction, then a week or a fortnight might go by before the channel tides would again be suitable for the landing.

Gen. Lord Hastings Ismay: We returned to London in an agony of uncertainty. If the bad weather persisted for another two days, Overlord would have to be postponed for at least a fortnight. The troops had already been briefed. What was to be done with them?

De Guingand: Officers ran to send the signals to the ports and the airfields. All over England, the machine sighed down into a standstill. There was nothing now to do except wait.

Lt. Dean L. Rockwell, flotilla commander, LCT-535: Should the weather make the landing unsafe, we were to be notified by a simple message called “Post Mike One.” And sure enough, early in the afternoon of June 4, a picket boat came alongside LCT-535, from which I was commanding the 16 landing craft, and handed me a telegram, which I still have, which simply says, “Post Mike One.”

Winston Churchill, prime minister of Britain: All convoys at sea turned about and small craft sought shelter in convenient anchorages. Only one large convoy, comprising 138 small vessels, failed to receive the message, but this too was overtaken and turned round without arousing the suspicions of the enemy. It was a hard day for the thousands of men cooped up in landing craft all round the coast.

Stagg: There was in fact only one day left for D-Day at that time: Tuesday, June 6. But at the time of the postponement, there was no indication, and certainly no reason for believing, that the weather on June 6 would be more favorable than on June 5.

Then, the unexpected happened. On the night of June 4, Maureen Flavin, a young Irish postal clerk who worked with her future husband, the keeper of the Blacksod lighthouse on the northwestern coast of Ireland, posted data that caught the attention of Stagg’s team.

Maureen Flavin Sweeney, postal clerk, Blacksod, Ireland: Our reports were the first to show any change coming in for good weather or bad weather. There was a query [from London] at around 11 o’clock. And then there was a second query. A lady with a distinct English accent requested me to “Please Check. Please Repeat!” We began to look at the figures again. We checked and rechecked and the figures were the same both times so we were happy enough then.

Lt. Robert Dale, flying officer, weather reconnaissance unit, RAF Station Wyton, Royal Canadian Air Force: There were probably four or five reconnaissances [that we flew] to keep plotting where the front was. The weather was really bad. The flights were 3½ hours — in a Mosquito, you would cover a lot of territory in 3½ hours. I got the feeling they already had the picture of things in their minds. I think we just confirmed their thoughts about what conditions would be like in the next 24 hours over the channel.

Petterssen: In the early hours of June 4, a sudden and major reorganization of the atmosphere over the Atlantic sector threw forecasters into confusion.

Stagg: Between the passage of the cold front and the approach of the depression, there could be an interlude of improved weather, and this interlude — if long enough and if it occurred at the right time — might just allow the first two critical sets of assault landings to be launched, at dawn and at dusk, on the same day. And that day could be Tuesday.

De Guingand: From the meteorologists, this time, there was a definite flicker of hope. Most unexpectedly, the weather had not worsened. It was dark, it was far from favorable, but it was no worse. And there was a hope that it would continue evenly like this for a few days.

Stagg: As on preceding occasions over the last four days — to me on that Sunday evening it seemed more like four months — the [commanders in chiefs] and their senior staff officers were assembling in the library as [Don] Yates and I entered the hall of Southwick House at 9.30 p.m. We waited till they had all arrived and immediately we were called in.

Eisenhower: He told us we might have a little bit of improvement in this weather next day. He said: “I’ll give you some good news.”

Stagg: I said, “Gentlemen, since I presented the forecast last evening some rapid and unexpected developments have occurred over the north Atlantic. In particular, a vigorous front — a cold front — from one of the depressions has been pushed more quickly and much farther south than could have been foreseen. This front is approaching Portsmouth now and will pass through all channel areas tonight or early tomorrow. After the strong winds and low cloud associated with that front have moved through, there will be a brief period of improved weather from Monday afternoon.”

Eisenhower: He predicted this good weather would last between 24 and 36 hours. It was still a chancy thing.

De Guingand: Adm. Ramsay was not enthusiastic. He was still worried about the build-up. And yet the chance was there. It could be done. Things could easily go wrong on the beaches, but still the landing was possible. [RAF Cmdr. Trafford] Leigh-Mallory, too, thought that he could manage to put up his bombers and fighters. But they would have to go in on a modified plan. Montgomery again was all for sailing. The men sat round the table going through the possibilities over again, trying desperately to bring the facts to the point where they would produce a hard inevitable decision. But that was not possible. The element of luck remained.

Just hours later, the same group gathered again at Southwick House in the midst of the howling gale that Stagg’s team had forecast.

Eisenhower: At 3:30 the next morning, our little camp was shaking and shuddering under a wind of almost hurricane proportions and the accompanying rain seemed to be traveling in horizontal streaks.

Montgomery: It was clear that if we had persisted with the original D-Day of June 5, we might have had a disaster.

Eisenhower: It certainly increased my confidence in Capt. Stagg, because 24 hours earlier, when it looked so nice, they said, “This is what you’re going to have,” and we had it. It was really storming.

Smith: There was coffee ready. I took a cup from a young flag lieutenant and moved toward the pleasant fire. All the commanders were there when Gen. Eisenhower arrived, trim in his tailored battle jacket, his face tense with the gravity of the decision before him.

Eisenhower: Stagg came in, a little grin on his face.

Stagg: All were in battle-dress uniform except Gen. Montgomery. Conspicuous in his customary front seat, he was dressed in a high-necked fawn-colored pullover and light corduroy trousers. Facing them, Gen. Eisenhower seemed as spruce and immaculate as ever. At the earlier meetings, the Cs-in-C and their staff chiefs exchanged pleasantries among themselves as they settled into their easy chairs and sofas. But at this meeting, as at the last, the atmosphere was somber. Faces were grave and the room was quiet.

Smith: There was the ghost of a smile on the tired face of Group Captain Stagg, the tall Scot. “I think we have found a gleam of hope for you, sir,” he said to Gen. Eisenhower, and we all listened expectantly. “The mass of weather fronts coming in from the Atlantic is moving faster than we anticipated,” the chief meteorologist continued.

Eisenhower: The forecast for the following day contained a gleam of hope.

Smith: They were giving us about 24 hours of reasonable weather. That was all.

De Guingand: Eisenhower came forward. “This is a decision which I must take alone,” he said. “After all, that is what I am here for.”

Smith: The silence lasted for five full minutes while Gen. Eisenhower sat on a sofa before the bookcase which filled the end of the room.

Eisenhower: I sat silently just reviewing these things I’d say 35 or 45 seconds. My own chief of staff says five minutes — I know that — but five minutes under such conditions sounds like a year. I think after 30, 45 seconds, I just got up and said, “Okay, we’ll go.”

Smith: Finally, he looked up, and the tension was gone from his face. He said briskly, “We’ll go!”

Stagg: The relief that statement brought into the room was a joy to behold. Immediately after I had finished, the tension seemed to evaporate and the supreme commander and his colleagues became as new men. Gen. Eisenhower had sat, turned sideways, facing me, taut and tense. A broad smile broke over his face as he said, “Well, Stagg, if this forecast comes off, I promise you we’ll have a celebration when the time comes.”

Eisenhower: There was a definite brightening of faces as, without a further word, each went off to his respective post of duty to flash out to his command the messages that would set the whole host in motion.

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