Raiding St. Nazaire
, Part One
By David Lippman
April 2015

On March 27, 1942, Admiral Karl Doenitz, the head of Germany’s U-Boat arm, left his headquarters at Lorient on the Bay of Biscay, to inspect construction progress on the massive submarine pens being built at the St. Nazaire base on the River Loire. Greeted by the commander of the 7th U-Boat Flotilla, Lt. Herbert Sohler, Doenitz got the complete tour. In the course of the inspection, Doenitz asked Sohler, “What are you going to do if the British attack this place?”

Sohler told his boss that emergency orders had already been issued for such an eventuality, but it was considered unlikely that a British raiding force could sail up the Loire River, with its shoal water and mud banks, past an array of German guns, and land troops in the port to damage his facilities.

Doenitz was not convinced. He answered, “I should not be too sure.”

Neither of them knew it, but less than 24 hours before, a British force of one old destroyer, two new ones, and 18 smaller vessels, carrying 611 commandos and sailors, had sailed from Falmouth – to attempt just such an attack.

“Operation Chariot” owed its beginnings to the great sea chase of the German battleship Bismarck the year before, when the mighty dreadnought tried to head for St. Nazaire after being damaged in her battle with the British battleships Hood and Prince of Wales. The port had the only drydock on the French coast big enough to accommodate Bismarck: the Forme-Ecluse Louis-Joubert, named for the President of St. Nazaire’s Chamber of Commerce, but generally called the Normandie Dock, as it was built to construct the legendary 80,000-ton French liner Normandie, launched in 1932. The dock was 1,148 feet long, 164 feet wide, and lay roughly north to south.

The Normandie drydock.

The dock was also designed as the primary means of access from the man-made inner basins of the port to the Loire, with two caissons: one at the north end, facing the port, the other at the south end, on the Loire. Each caisson, or gate, was 167 feet long, 54 feet high, and 35 feet thick, built as sectional steel boxes, and weighed 1,800 tons. Ironically, the caissons were built by MAN in Germany.

Winding houses on the dock’s west side rolled the caissons into cambers to open it to ships. A pumping house near the south caisson controlled the water level in the dock. Thus the dock could handle either the functions of transit passage for shipping or construction and repair yard.

Now the immense drydock no longer accommodated French ocean liners, but German warships, and was a difficult target to put out of business. The dock was some distance up the Loire River, which made it safe from naval bombardment. The Royal Air Force lacked both the bombers and precision ability to hit such a narrow, well-defended target.

Yet the Admiralty needed it demolished. While Bismarck lay at the bottom of the Atlantic, it taken nearly the whole Royal Navy to put her there. Now Bismarck’s twin sister, Tirpitz, had taken up residence in Norway, poised to break out on a raiding voyage of her own into the shipping lanes that connected Britain with Canada and the United States. If she broke into the Atlantic, and either suffered damage or needed a refuge, she might wind up at St. Nazaire, representing a continuing threat to the British sea lanes.

And that couldn’t happen at a worse time for Britain and her allies. Despite American entry into the war after Pearl Harbor, Britain was at her lowest ebb. Hitler’s strutting armies occupied most of Europe and much of the Soviet Union’s industrial and agricultural regions. In North Africa, General Erwin Rommel’s Afrika Korps was gaining an immense reputation and stunning victories by running rings around the larger British Eighth Army. German U-Boats were savaging convoys off America’s East Coast as well as in the North Atlantic. In February, the German battle fleet embarrassed the British further when two battleships, Scharnhorst and Gneisenau, raced up the English Channel from Brest to Wilhelmshaven, defying the Royal Navy and RAF. Since attacking Pearl Harbor, Japan’s forces had proved almost unstoppable, seizing Hong Kong, the Dutch East Indies, and the vaunted fortress at Singapore by February and March. At home, the people were wearied by endless privations: the destruction caused by bombing, the hard rationing and the privations and shortages that left the average Briton exhausted. The nation needed a victory.

The Normandie drydock (top center) and St. Nazaire's Inner Basins.

Fortunately Britain still had energetic men with vision, and one of them was King George VI’s cousin, Admiral Lord Louis Mountbatten, head of Combined Operations. His brief was to develop the techniques by which Britain and her allies would re-enter the continent and while doing so, test them out with highly-skilled and motivated Commando forces which would make raids on minor and major objectives.

On January 27, 1942, Mountbatten was asked by the Admiralty to look into a solution to the St. Nazaire problem. Mountbatten had already been looking into it as a possible raid target, noting that the Loire River estuary had a defensive flaw: vessels of light draft, like motor launches, could approach the port over its mud flats at high water or during extraordinary spring tides. It was indeed possible to get a force in to St. Nazaire. Getting out would not be so easy.

Mountbatten summoned RAF Wing Commander Marquis de Casa Maury, his intelligence chief, and asked if Casa Maury had any material on St. Nazaire.

Casa Maury replied, “St. Nazaire! Yes – heaps!”

It turned out that the RAF had done a superb job of photo-reconnaissance of the port, and Casa Maury even had technical drawings of the Normandie dock caissons. And the dock was identical to the King George V Dock in Southampton. Its owner was summoned to Combined Operations Headquarters at Richmond Terrace in London to provide whatever technical advice he had, and did so.

As the British planners studied their maps, they figured out more about the port’s defenses and objectives. St. Nazaire had no mines or barbed wire – probably because the estuary was too narrow to permit their use.

The U-Boat pens, built with Teutonic efficiency and Krupp concrete, were in the inner harbor, the St. Nazaire Basin, and thus nearly impossible to breach with the RAF’s bombs of the time or a commando raid. But there was a lock gate that led to the Basin, near the Normandie Dock. The British theorized that if torpedoes were jammed into that lock gate, the Basin would be rendered tidal, and the U-Boats would not be able to use the Basin as a base.

The British added more useful objectives to the raid plan: underground fuel tanks that supported the U-Boats, other lock gates to the St. Nazaire Basin’s South Entrance, the Normandie Dock’s winding houses and pumping house, and the power station.

But the primary objective was the drydock, and the problem was how to destroy it. British Commandos could wreck the pumping and winding houses with well-placed explosive charges, but there was no guarantee they could get there or that such damage would wreck the drydock.

The “terrifying solution “ was to use an “explosive ship” that would steam into the Loire Estuary, ram the drydock and blow itself to pieces, ripping apart the south caisson. That would require converting a destroyer – no smaller craft would do – into a floating bombshell, jammed with explosives. Her crew would have to sail her under enemy fire precisely into the south caisson, and then be evacuated on supporting smaller craft.

Now the plan began to come together. Commandos would assault the port in three groups: one from the destroyer to blast the pumping and winding houses and wreck the fuel tanks, a second from a column of motor launches in the inner harbor to destroy gun positions and bridges leading from the port area to the rest of the town and set up the headquarters area, and a third from another column of motor launches to land near the Old Mole in the southern part of the port area to destroy the power station and set up a bridgehead to cover the evacuation. Everybody would be withdrawn through the Old Mole and sail home.

To wreck the lock gates in the inner harbor, Motor Torpedo Boat 74, under Lt. Michael “Micky” Wynn, was assigned. His MTB already carried two 1,800-ton explosive torpedoes fitted with delay action fuses. Once fired, they would sit on the bottom and explode at a pre-set time. They were originally to be used to attack the German battleship Scharnhorst in her lair in Brest, but that ship had already fled the coop, leaving MTB 74 and “Wynn’s Weapons” without a job. MTB 74 was assigned to the task.

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David H. Lippman, an award-winning journalist and graduate of the New School for Social Research, has written many magazine articles about World War II. His new book, World War II Plus 75, is now available. We're pleased to add his work to our Daily Content.