Convoys, Raiders and Escorts
in the Early Battle of the Atlantic
By Doug McNair
May 2006

It’s said that generals are always fighting the last war. But when World War II broke out in Europe, the British Admiralty had a difficult time applying some of the most important lessons from World War I to the new conflict in the North Atlantic. In the 20th Century, Britain’s ability to wage war depended entirely on a constant stream of seaborne imports. German U-Boats in World War I did massive damage to the merchant vessels which constituted this lifeline — far more than the surface ships of the Imperial High Seas Fleet ever did. The U-Boat threat was only brought under control when the Allies began packing their merchant vessels into convoys and guarding them with destroyers and other craft equipped for anti-submarine warfare.

Convoys in Crisis

But between the wars, British readiness to deal with a renewed U-Boat threat declined dramatically, for several reasons. Ironically, one of the top reasons was the invention of ASDIC, the British precursor to the U.S. Navy’s SONAR. British faith in ASDIC’s ability to detect U-Boats and render them vulnerable was so great that they fitted out 150 aging destroyers with it and left it at that. Juxtapose this against a merchant fleet of 3,000 ships and you begin to see the problem. Much like a present-day conflict where politicians expect an army of 135,000 to pacify and protect a nation of 26 million, the Royal Navy’s failure to put enough hulls in the water needlessly turned the convoys (and their escorts) into fish in a barrel during the early years of the war.

A typical North Atlantic convoy, 1941.

Another problem stemmed from a technological deficiency above the water line. Radar was not in widespread use by the British when the war started, and certainly not by aging merchant vessels. Combine this with the need to maintain radio silence and blackout conditions, and merchantmen were all but blind at night. In order to keep from falling out of line or colliding with other ships in the dark, most merchant captains had no choice but to simply steer by the shadow of the next ship in line.

With no preset plan for keeping the convoy together, two neighboring convoy ships would often make the mistake of using each other as reference points. When the sun came up they’d still be steaming neatly in line . . . but the rest of the convoy had vanished. Convoy ships falling out of line, steaming off in the dark and becoming “rompers” was an unending problem — one which the German player in our Second World War at Sea: Bismarck game can use to his advantage.

The Evolution of the Raiders

In the first year of the war, the lion’s share of merchant ship losses were ships sailing independently, not in convoy. This was largely a matter of preference. U-Boat commanders preferred to attack defenseless merchantmen rather than risk detection by depth charge-equipped convoy escorts. But the extremely sparse protection of convoys at that time (some had just one destroyer escorting them, and others had nothing but 4-inch guns on the decks of the merchantmen), plus the demonstrated ineffectiveness of ASDIC-equipped British hunter-killer ship groups, emboldened some U-Boat commanders. Before long, they discovered that Admiral Dönitz’s World War I tactic of approaching a convoy on the surface at night let them get right in among the convoy ships, undetected by ASDIC. This was because ASDIC had the fatal flaw of being ineffective at detecting small targets on the surface. Combine this with the lamentable lack of combined-operations training for escort ships, and escort commanders soon found themselves chasing U-Boat shadows while merchantmen exploded all around them.

Two types of raider. Submarine U-47 and battle cruiser Scharnhorst, 1939.

German surface raiders also got worldwide attention for their attacks on Allied merchant shipping in the early war years. But like the U-Boats, they did most of their damage to lone merchantmen. All the victims of the pocket battleship Graf Spee (a principal performer in our Cone of Fire Classic Wargame Proposal) were lone freighters. And when her sister ship Admiral Scheer encountered Convoy HX84 on November 5, 1940, the lone escort (armed merchant cruiser Jervis Bay) was able to keep her busy long enough for the convoy to scatter. Only five merchant ships out of 37 (plus Jervis Bay herself) fell to Admiral Scheer’s guns. The cruiser Admiral Hipper had better luck against an unescorted convoy in February 1941, sinking seven out of 19 ships. But this was paltry compared to the victories which U-Boats were racking up by then. Indeed, old Jervis Bay’s effectiveness against the state-of-the-art Admiral Scheer proved that any future German surface raiders would have to sail together in task forces to have a chance at disrupting the convoy system. This realization helped set the wheels in motion for the launch of the most famous of all German convoy-raiding task forces: the Bismarck and the Prinz Eugen.

Flower Power

As the war progressed, Royal Navy ship production slowly caught up with the escort needs of the convoys. Early assistance from the U.S. in the form of 50 lend-lease World War I destroyers helped, as did the introduction of Black Swan-class sloops later on. But the backbone of the new escort fleet was the Flower-class corvette.

HMCS Sackville.

Originally designed as coastal escorts and minesweepers, corvettes rolled horribly on the high seas, even in good weather. But they were tough and seaworthy, highly maneuverable, and quick and cheap to build. Constantly upgraded over the war years, these small, unglamorous ships took the brunt of the fighting against the U-Boat wolfpacks, and took it well. Improvements in anti-submarine weaponry like the Hedgehog and Squid gave the corvettes better ways to deal with the U-Boats over time. And increased production of new classes of escort vessels, plus the addition of air cover from escort carriers and long-range land-based ASW planes, finally brought the U-Boat menace under control in May 1943.

It’s tough to find much small-scale living naval history today, but we’re lucky that the Royal Canadian Navy’s forces in the North Atlantic included a large number of corvettes. HMCS Sackville, “The Last Corvette,” serves as Canada’s Naval Memorial at Halifax, Nova Scotia. You can visit her online, take a photo tour, and read her history and action reports. Or you can hear her history sung in all its glory by my favorite shantyman Tom Lewis on disc and at seaside festivals around North America and Europe.

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