By conducting more offensive sweeps and trolling astern of a convoy to find shadowing U-boats, Royal Canadian Navy escort vessels decided they could set the tempo in the fight against enemy subs. 

German operations against convoy ON 115 ended in the fog of the Grand Banks on Aug. 3, 1942 (A Night Of Furious Action, March/April 2014).

Acting Commander D.C. Wallace, who was the captain of His Majesty’s Canadian Ship Saguenay and the original senior officer of the escort group, was certainly pleased with the outcome. So was the Royal Canadian Navy staff in St. John’s, Nfld.

The fast moving, westbound convoy had been dogged by U-boats from early contact while still in the eastern Atlantic on July 26 to the final battles with Wolf Pack Group Pirat on the night of Aug. 2-3. Two ships from the convoy were sunk and one damaged. In exchange, one U-boat had been sunk in mid-ocean and the international press had reported that HMCS Sackville had destroyed U-552 and may have sunk another.

Wallace attributed the successful defence of ON 115 to aggressive sweeps by his two destroyers. Since neither the escort group C.3 nor the convoy carried a HF/DF (High Frequency/Direction Finder) set, which would have tracked U-boat HF reports as they made contact with ON 115, Wallace relied on MF (Medium Frequency) homing beacons used by shadowing U-boats to draw other U-boats to the battle.

Medium Frequency beacons were routinely used for basic navigation, and all Canadian escorts carried a MF/DF receiver. Medium Frequency fixes were much less precise than HF, but Wallace used them sensibly to get a general idea of where the U-boats were, how many were in contact, and when to alter ON 115’s course away from them.

High-speed sweeps by his destroyers forced the shadowing U-boats to dive or face attack. But MF/DF was still no substitute for HF/DF, as Wallace commented. The captain of HMCS Skeena, Lieutenant-Commander Ken Dyer, agreed. The real need was for HF/DF sets.

Rear-Admiral Leonard Murray and his staff in St. John’s were focused almost entirely on the destruction of U-558 and the possibility that Sackville had sunk U-552 and damaged or sunk two more. Vice-Admiral R.M. Brainard, United States Navy, stationed at Argentia, Nfld., controlled escort operations in the western Atlantic and he too was focused on the positives from ON 115. Brainard thought Wallace made effective use of destroyer sweeps, and now petitioned his own navy to replace the slow Coast Guard Cutters in group A.3 with USN destroyers so the token American group in the mid-ocean could do the same.

None of the Canadian or American staff appeared concerned about the comments from the commanding officer of HMCS Sackville that Wallace’s aggressive tactics early in the passage left the rump of C.3 without its destroyers and its senior escort officer when Group Pirat came calling on the night of Aug. 2-3. “It would seem to be most unfortunate,” Lieutenant-Commander Alan Easton wrote in his escort’s Report of Proceedings, “that the senior officer was absent at the critical time as far as members of his own group were concerned.” Easton’s ship and what remained of C.3 “were left rather on a limb…” after the destroyers departed on the Grand Banks due to lack of fuel.

As a rule, the British staff at Western Approaches Command (WAC) in Liverpool needed no encouragement to see the RCN as a glass half empty, so it’s not clear if Easton’s comment about Wallace’s absence on the night of Aug. 2-3 was the prompt they needed to see the battle for ON 115 in a sharply different light.

All that is clear is that by mid-September, when copies of the escort’s Reports of Proceedings finally reached Liverpool, the WAC staff saw the battle for ON 115 as a shambles. The Deputy Chief of Staff (Operations), Captain R.W. Ravenhill, Royal Navy, considered Wallace’s use of destroyer sweeps “reckless” and his 90-degree course alterations of the convoy left it “zigzagging across the ocean.” It was agreed at WAC that the whole affair needed to be referred to the highest levels—so they framed their comments accordingly.

The harshest comments on C.3’s performance with ON 115 from WAC staff came from the staff officer, Anti-Submarine, Commander C.D. Howard-Johnston, RN. He described Wallace’s destroyer sweeps as “a reckless expenditure of fuel and disregard for the objective which must always include ‘timely arrival.’”

Howard-Johnston stated: “I find in this story the ignorance of inexperienced officers who think that they are being offensive by acting in a reckless manner and without real consideration of the obligation to protect the convoy throughout the period it is entrusted to them.”

Fortunately not all WAC staff officers were so ill-disposed to the Canadians. The convoy officer suggested that rescue ships fitted with HF/DF ought to be specially assigned to RCN escorted convoys, and the signals officer wanted to push for fitting the equipment to RCN destroyers as soon as possible. As the signals officer commented, the passage of ON 115 revealed the value of HF/DF and “what a disadvantage an escort group who is not so fitted finds herself.”

Clearly they understood Wallace’s dilemma. The recent RCN official history of operations, which has thoroughly reviewed the evidence from both sides, refutes the claims by both Ravenhill and Howard-Johnston that Wallace’s aggressive use of destroyer sweeps and course alterations were reckless. In fact, it was quite the contrary.

In No Higher Purpose, Vol. Ⅱ, Part 1 of the RCN official history W.A.B. Douglas points out that “German records show Wallace’s destroyer sweeps and large evasive course alterations after dark had in fact been effective in keeping [U-boat pack] Wolf…at bay.”

The battle around ON 115 on Aug. 2-3 in the fog also revealed the urgent need for modern Type 271, 10-cm search radar. Here, too, some WAC staff understood the handicap C groups (escorts) operated under. By the time WAC staff assessed the reports of ON 115 it was clear all three of Sackville’s U-boats had escaped, although two of them were heavily damaged. U-43, which Sackville blew to the surface like a breaching whale, made port in France. U-552, reported sunk by American newspapers, slipped beneath the waves after Sackville’s four-inch shell struck her conning tower.

Easton never found her again, despite help from HMCS Agassiz. As it turned out, Sackville’s shell blasted away the external hull, leaving the interior pressure hull intact. But the explosion severed the main engine air induction and exhaust pipes, and wrecked the rear periscope. A great deal of water poured into U-552 before it could be stopped. Kapitainleutant Erik Topp saved U-552 and ended the war as Germany’s third highest scoring U-boat ace. But, as we’ve seen, it was a very close run thing.

As the WAC radar officer commented, “Sackville’s two U-boats would have been a gift if she had been fitted with RDF [Radio Direction Finding, the original British term for the American acronym radar] Type 271.”

Clearly, modern radar was needed for C groups, too.

The issue of drastic course alterations was pushed up the line from WAC to the Admiralty and eventually to Washington, D.C. The RN’s real gripe was with the convoy routing people in Washington, and with their micro-management of ON 113 which led to it turning a complete circle in the mid-Atlantic and running into the U-boat Wolf Pack it was trying to avoid. Wallace’s course alterations of ON 115 to avoid suspected U-boats based on MF intercepts touched a sore spot.

The RCN official history observes that the harsh comments on the escort of ON 115 by WAC senior staff in mid-September “betrayed doubts at Western Approaches about the RCN’s proficiency.” To a large extent, the sharp comments evident from senior WAC staff throughout 1941-43 arose from ignorance of the problems confronting the RCN and the reasoned efforts (not always seen as such in Liverpool) of intelligent Canadian officers to solve them with what little they had.

The wave of U-boat attacks on fast, westbound convoys, for example, was noted in St. John’s, not least because most of them fell on RCN escorted convoys. Commander James “Chummy” Prentice, perhaps the RCN’s most ardent U-boat hunter and still in command of the corvette Chambly, proposed to his Captain (Destroyers), E.R. Mainguy, on Aug. 1 that C groups do more offensive sweeps around a convoy in an effort to trap U-boats as they made their approach. Prentice feared that when the great weight of U-boats feasting off the U.S. and Caribbean coasts shifted back to the mid-ocean—“when the real attack [in the mid-ocean] comes”—the RCN needed to be able to respond.

Prentice clearly understood that without HF/DF and Type 271 radar to provide timely tactical intelligence, RCN escorts could not set the tempo of the battle, they could only react. By pushing out sweeps and trolling astern of the convoy to find shadowing U-boats that were creeping up for attack, the RCN might be able to set the tempo themselves. At the very least they might sink more enemy subs.

Mainguy dismissed Prentice’s scheme rather summarily. “I think Chambly credits the Hun with too much intelligence,” Mainguy noted on Prentice’s proposal, “and the average Corvette CO [commanding officer] with much too much.” The Germans, Mainguy claimed, had little idea of what was going on during a convoy battle, and “even the escorts themselves do not know if it’s Christmas or Easter.”

As we shall see, Mainguy’s tendency to write flippant or amusingly dismissive comments of Reports of Proceedings did not serve the RCN well in Liverpool.

In any event, there was little in the action at sea between ON 115 and the time when its reports were assessed at WAC in mid-September to warrant the sharp criticisms from Ravenhill and Howard-Johnston. In fact, Canadian success at sinking U-boats and defending convoys continued through August and early September.

On Aug. 2, as C.3 fought U-boats in the Grand Banks fog around ON 115, escort group C.1 took over the slow eastbound convoy SC 94 southeast of St. John’s for the long passage to Britain. The group had last fought a battle in June around ON 100, and its core remained intact: the River-class destroyer Assiniboine, with Lt.-Cmdr. J.H. Stubbs, RCN, in command, and the corvettes Battleford, HMS Dianthus and HMS Nasturtium. Three other corvettes had joined the group since June: HMCS Chilliwack, HMCS Orillia and HMS Primrose. So C.1 was quite strong, seven escorts, although only one was a destroyer. The senior officer was Lt.-Cmdr. A. Ayer, Royal Naval Reserve, in command of Primrose. For passage to England, Assiniboine embarked the RCN’s official historian, Gilbert Tucker, PhD. Shortly after C.1 joined SC 94, Tucker would witness one of the most remarkable actions in the history of the RCN.