p26  Chapter II

Operations Room.
The Problem of Invasion

"Only officers designated by the senior staff operations officer are to be admitted to this room. . . ."

— Sign on the door of XII Fleet Operations Room

Once up the short flight of stone steps and identified by the sentry, one stood in the wide and gloomy hall of Number Twenty. There was a marble floor from which ornate columns rose to shadowy plaster moldings. To the right led a passage into the Admiral's country, where one would find the office of the senior staff operations officer, the flag secretary, and finally, in what had been a large living room, Admiral Stark himself, seated before a wall map of Europe, with his four-star flag on one side and the American flag on the other.

If one turned to the left from the entrance lobby there would be the chiefs of Army staff.

In upstairs rooms one found naval intelligence, political warfare, shipping, anti-submarine, medical, air liaison, personnel,  p27 and the other services and specialties required in this complex command.

It was toward the rear of the entrance lobby, however, and to the left that the heart of the building lay, right next to communications. Here was the joint Operations Room.

In this Operations Room, after the day staff left for supper about six, one senior officer from the Admiral's staff nightly stood the operations duty watch. Until eight in the morning, he was the U. S. Navy. All incoming dispatches were brought to him. He called or sent messengers for officers when the matters were too urgent or beyond his ken to handle.

In this windowless, double-locked room, on one wall was a large map of the North Atlantic with convoy positions of the day plotted. On another wall was a large chart of British home waters and the Channel area.

Scattered over the floor area was a miscellaneous assortment of splintered oak desks, oddly matched file cabinets of various sizes and a large oak chart table.

Among this heap of hastily gathered office furniture, during the day various members of the operations staff sorted signals, compiled data on troop movement, convoys and port statistics. In the filing cabinets reposed plans of various operations, some completed, some contemplated, some in the "appreciation" stage.

Except for the occasional visit of an officer seeking to consult one of the documents or checking on a specific situation, after supper the operations duty officer held sway alone.

After midnight when the dispatch rider had brought in the last of the Admiralty signals and the U. S. Naval communicators  p28 had quieted down, the three phones on the oak desk at the far end of the room fell silent. Then this room was the place to study the war.

One knew what convoys were under attack, how many ships had been sunk, what air cover and surface escort were planned. One could read not only the U. S. but the Admiralty dispatches from all over the world.

Now and again in a routine message one might find such trivial but exciting news as the name of a friend promoted or under travel orders back to the States or to London. The name of a familiar ship would suddenly appear. The forces engaged in Sicily could be estimated. The flow of planes and men to the U. K. could be determined. Out of facts such as these future moves might be guessed and certainly capabilities for future action known.

Usually about the time life quieted down at the Navy Operations desk, the U. S. Army air duty officer, who occupied a neighboring map room, had his program for the night plotted. The number of planes and the weight of bombs for the night's objectives were laid out in a red ribbon on the air map of the continent, the number of operational and reserve planes at the various fields had been checked and tabulated. There being no door between these two operations rooms, there was always the hot plate and kettle that could produce a cup of tea and a chance for a friendly smoke and talk.

Since the night duty staff officers of all the services had to know all that was going on — and, for the most part, it was their digest of communications and situation reports that would guide the briefing officers in the morning — security was no problem. Here at least was one place in  p29 London where it was safe to talk freely about top secret information.

Furthermore, this talk could spring from realism and facts rather than the speculation of the kind ordinary military men, who knew only their own segment of the total scheme of things, might indulge in.

It was this room which made Number Twenty the key to the future.

The British civilian passing by in the street was right in his feeling that in that building lay certain knowledge of the move to come, this big move across the Channel for which the whole world waited.

In the quiet hours of the night, over endless cups of tea and cigarettes, there were few better opportunities to examine this problem.

There was always one insurmountable hurdle in these discussions of invasion, however, for which there seemed to be no answer.

Even if the North Atlantic convoys could complete the huge required build‑up in the U. K., even if England could hold the men and armor and vehicles and stores required for assault, how could that assault be mounted and in what enemy port could it be landed?

The hardest part of that question was the last half of it. Assuming that the cross-Channel invasion could be attempted from the miniature British ports, over the narrow roads of the south and east coast, the sticky part of it was: where would all this mechanized army and its supplies be handled on the Far Shore?​1 With British ports, bad as they were, strained to utmost capacity to handle just the build‑up,  p30 how would any bomb-damaged captured port ever handle the huge tonnage requirements of an assault?

It was easy to visualize how a port like Le Havre, for example, would look after the weeks of preliminary Allied air and sea bombardment had smashed its fortifications thoroughly enough to allow transports, Liberty ships and merchant vessels to unload. Dock machinery, derricks, and sheds would be smashed and the quayside heaped with wreckage that would take weeks to clear. Ships would be sunk at the dockside and in the narrow channels. Again it could take weeks, even months, for salvage forces to clear these wrecks. There was all the history of the African ports to supplement the imagination. Retreating Germans could be counted on to apply the finishing touches by dynamiting any remaining structures and strewing the harbor with mines.

Conversations about the invasion in the late hours of the operations duty always fetched up against this puzzling stubborn wall to further thinking.

The Operations Room conversations usually brought up the fact that Hitler also must have pondered the reverse of the Allied problem in 1941 and 1942. With England beaten defenseless to its knees from the blitz air attacks of those years; with the Germans known to have hundreds of Dutch and Rhine barges at their disposal, the urge to invade must have been strong indeed. There were even the German songs of sailing, "Wir segeln nach England," that were so well known as to have been tauntingly hummed in London. But no serious move had been made beyond certain small assembly operations that looked like exercises. No workable plan had been found by the German General Staff.

Since, for Germany, apparently no cross-Channel scheme  p31 would work, the concept of Festung Europa replaced it and took hold. It became the whole German planning concept. With hundreds of thousands of enslaved civilians augmented by prisoners of war, labor to pour concrete, build strong points, move up guns to the coast and the ports, was plentiful. It was easy to see how the idea of the "Atlantic Wall" and the "Impregnable Fortress of Europe" was better suited to German needs than the idea of invasion.

By now this fortress was well along in its building. How could Allied Forces, as invaders, necessarily with inferior numbers, successfully crack this iron and concrete wall of the Fortress of Europe?

It was well enough for American magazines to draw menacing fat arrows out of England across the Channel to the obvious French ports, from Boulogne in the Pas de Calais area down to Cherbourg at the tip of the Cotentin Peninsula.

But these arrows on paper, no matter how formidable or how red or how thick, could not represent more than a five-division movement — into a derelict-filled port.

Germany was known to have some sixty-four divisions uncommitted on the eastern front, in reserve for any Allied invasion move.

Bolder sweeps of the journalistic invasion arrows cut in a neat curve down to the Brittany Peninsula and the port of Brest. But here the realism of the Operations Room could readily intervene. The airman from the neighboring Air Operations Room would quickly cancel any such proposal and point out simply that fighter cover could not operate at that range with more than a minute or two of fuel left for combat in the zone of operations. The farthest limit would  p32 be the Cotentin Peninsula, and that meant the Pas de Calais small ports, or Le Havre, or Cherbourg.

His naval companion could as readily point out the bloody and futile consequences of the Dieppe Commando raid​a across the enticingly near and narrow part of the Channel in the Pas de Calais. Action in this Pas de Calais area would be met by concentrated fire from the heaviest guns in all Europe, for the Germans had moved into this obvious invasion area all the big guns from the Maginot Line. They were now in position behind reinforced steel and concrete and so thickly placed that anyone who had ever run a Channel convoy past Dover would testify that the gun flashes sprang up as close together as jets of flame in a gas log.

Le Havre and Cherbourg were equally heavily fortified, as destroyer raids from Portsmouth had already fully tested.

What, then, was the answer?

On what port finally was the majestic concept of the long-awaited plan for invading Europe to be based? Such a plan, known by the code word "Over­lord," had been ratified in Quebec in July. It had the status of an approved operation.

The Combined Chiefs of Staff papers 307/2,3 reached London on 4 September, 1943. Those duty officers who glimpsed these papers learned the answer.

No port would be captured.

Instead, the assault would land on the open beach at the base of the Cotentin Peninsula — side-stepping the fire from Le Havre on the one hand and Cap Barfleur and Cherbourg from the tip of the peninsula.

Recognizing that weather could interrupt the flow of supplies beyond the danger point, the Combined Chiefs of Staff papers provided for the construction of two completely artificial  p33 harbors, one American, one British, off the assault beaches.

This was to be accomplished in fourteen days or less. Gigantic breakwaters, together with piers and steel roadways inside the breakwaters, were to be fabricated in England, towed across the Channel with the assault forces, and constructed on the enemy shore with a great force working night and day beginning on D + 1.​2

The code name given to this project was Mulberry. It was the basic assumption​3 on which the whole Over­lord plan for the invasion of Europe was to be undertaken.

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The Author's Notes:

1 A term used to indicate the prospective invasion beaches of France.

2 D‑day plus one day.

3 Other assumptions: (2) That the German Air Force be reduced to relative inactivity; (3) That preliminary Allied air activity would destroy such German shore fortifications as existed in the area.

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Thayer's Note:

a See note, p36.

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