The Canadian Escort Group C4 (Lt-Cdr Piers) consisting of the destroyer Restigouche and the 4 corvettes Algoma, Amherst, Arvida and Celandine (RN).

In the convoy there is the rescue ship Stockport equipped with HF/DF.

The wolfpack Veilchen of 13 boats U-71 (Oblt von Roithberg) *, U-84 (Kptlt Uphoff) *, U-89 (Korvkpt Lohmann) *, U-132 (Kptlt Vogelsang) *, U-381 (Kptlt Graf von Pückler und Limburg), U-402 (Korvkpt Freiherr von Forstner) *, U-437 (Kptlt Schulz), U-438 (Kptlt Franzius) *, U-442 (Korvkpt Hesse) *, U-454 (Kptlt Hackländer), U-571 (Kptlt Möhlmann), U-658 (Kptlt Senkel), U-704 (Kptlt Kessler)

Stationed South of Newfoundland on the beginning of the operations: U-520 (Kptlt Schwartzkopff), U-521 (Oblt Bargsten) *, U-522 (Kptlt Schneider) *

* U-boats that fired torpedo or used the deck gun

The patrol line Veilchen is formed on Oct 24th and stationed East of Newfoundland with the purpose to intercept eastbound convoys. So when U-437 reports the westbound ON-140 on the 28th, no action is taken.

On the 30th U-522 detects the convoy. All U-boats of the patrol line plus U-520 and U-521 try to close in fast. The many radio signals of the U-boats leave the Allied Command no doubts : the convoy is in imminent danger. The British destroyer Walker and the Canadian destroyer Columbia of the Western Local Escort remains temporarily with the convoy and air escort is provided. U-520 and U-658 fall victim to air patrols that day. An attack of the U-522 on the Columbia has no success.

On the next day U-522 and U-521, the 2 boats near the convoy are driven off by the escort and air patrols, but on Nov 1st U-381 sights the convoy again. The Western Local Escort Destroyers are short on fuel and return to port.

The convoy enters now the 'black pit ' and with only 5 escorts to deal with a complete wolf pack, the situation looks desperate to the escort commander. However, he manages during the first part of the night to keep the U-boats at bay. The destroyer makes large sweeps at the rear of the convoy and prevents any U-boat to close in or catch up with the convoy. The Celandine makes offensive sweeps towards HF/DF contacts.

After midnight, the escorts are overwhelmed by the U-boats, who attack in quick succession. U-402 is the first to reach the convoy and torpedoes one ship, which is later finished of by U-84. U-381 misses the Restigouche. U-402 and U-522 attack two times, both simultaneously, with an interval of three hours. U-402 sinks 3 ships and damages one, who is finished off by U-438 and U-522 sinks 2 ships and damages one, who is finished off by U-521. U-442 misses the convoy.

By day on the 2nd, the corvette Moosejaw joins the escort. U-132, U-402 and U-522 keep contact with the roughed-up convoy. U-522 makes a daylight submerged attack in the late afternoon and sinks another ship.

In the evening a thick fog comes up. The U-boats loose contact and no attacks are made. But also the convoy is scattered when the convoy commodore tries to elude the U-boats with several course changes. The destroyer Vanessa is detached from convoy HX-212 and reinforces the escort of SC-107.

When dawn comes up, U-71, U-84, U-381, U-402, U-438, U-521, U-522, U-571 and U-704 make contact in turns but cannot exploit the favourable situation. The escort keep the U-boats at bay. Only U-521 sinks one tanker in two approaches. U-438 has misses on stragglers.

After dark, U-89 attacks and sinks the commodore ship. U-132 sinks 2 ships and damages one, finished off by U-442 later. One of its victims is an ammunition ship. Half an hour after being torpedoed the ship disappears in a tremendous explosion, which leaves many ships in the convoy to believe that they themselves have been torpedoed. But ironically the only victim of this explosion might have been U-132 itself. This U-boat goes missing after the operations. Further attacks by U-71, U-438 and U-442 have no success.

Some ships leave the convoy for Iceland: the rescue ship and 2 tugs overcrowded with survivors, one tanker and 2 corvettes. From Iceland 3 USN escorts arrive in the evening: the destroyers Schenck and Leary and the cutter Ingham. They are too late however to prevent U-89 from sinking another ship.

On the 5th Nov the convoy leaves the 'black pit' and Liberators of Sqdn. 120 RAF drive off U-84, U-381, U-442, U-454, U-521, U-522 and U-571. The planes are guided by HF/DF bearings from the Restigouche. U-89 is damaged by one of the aircraft.