'Leopard' (i) was a U-boat wolfpack operation, in tandem with 'Wotan' (ii), in the Atlantic against the ONS.136 and SC.104 convoys (12/19 October 1942).

The wolfpack comprised U-254, U-353, U-382, U-437, U-442, U-597, U-620 and U-662, and for the loss of Kapitänleutnant Wolfgang Römer’s U-353 and Korvettenkapitän Eberhard Bopst’s U-597 sank one 6,098-ton ship of the SC.104 convoy.

From 8 October the 'Panther' (iii) wolfpack was created out of newly arrived boats as well as a number of those which had just been involved in the battle against the HX.209 convoy. The wolfpack therefore comprised U-57, U-84, U-254, U-260, U-353, U-437, U-442, U-454, U-575, U-597, U-602, U-706 and U-753, joined over the next few days by U-301, U-382, U-441, U-443, U-563, U-610, U-620, U-621 and U-662.

During the evening of 11 October U-620 spotted and reported the westbound ONS.136 convoy of 36 ships accompanied by Commander A. A. Tait’s British Escort Group B3 (destroyers Harvester and Free Polish Garland, and corvettes Narcissus, Orchis and Free French Aconit, Lobélia and Roselys), and at this time U-254, U-353, U-382, U-437, U-442, U-597, U-620 and U-662 were detached as the 'Leopard' (i) wolfpack to engage this convoy.

In winds of between gale and storm force, however, only Bopst’s U-597 was able to reach a firing position, and made two unsuccessful attacks before being sunk on 12 October by a Consolidated Liberator long-range patrol bomber of the RAF’s No. 120 Squadron.

After this, only independents and stragglers were sighted. U-382 missed a destroyer and Korvettenkapitän Alexander von Zitzewitz’s U-706 sank the 4,265-ton British Stornest.

On 14 October the operation against the ONS.136 convoy was terminated and the 'Leopard' (i) wolfpack was redirected to the approaching SC.104 convoy. Six days earlier, on 8 October, the 'Wotan' (ii) wolfpack had been established in the area to the east of Newfoundland with U-221, U-258, U-356, U-410, U-599, U-607, U-615 and U-618, which had taken on fuel from Oberleutnant Wilhelm Grimme’s U-116 (lost to unknown causes on about 15 October) and U-118. Later additions to the 'Wotan' (ii) wolfpack were U-216 and U-661, which had been refuelled by the newly arrived U-463.

On 11 October Kapitänleutnant Ralph Kapitsky’s U-615 sank the 4,221-ton Panamanian El Lago, a straggler from the ONS.136 convoy. On the same day U-258 sighted a corvette of the escort for the SC.104 convoy of 48 ships supported by Commander R. Heathcote’s British Escort Group B6 (destroyers Fame and Viscount, Free Norwegian corvettes Acanthus, Eglantine, Montbretia and Potentilla, and the HF/DF-equipped rescue ship Goathland). Atmospheric conditions prevented the receipt of the contact report until 12 October, and the deployment of the 'Wotan' (ii) wolfpack was delayed by the sighting of the ON.135 convoy and Captain Fitz’s supporting US Escort Group A3 (US Coast Guard cutter Campbell, US destroyer Badger, British corvette Dianthus, and Canadian corvettes Rosthern and Trillium) by U-356.

Thus it was only during the night of 12/13 October that Kapitänleutnant Hans-Hartwig Trojer’s U-221 managed to close the SC.104 convoy: in three skilfully executed approaches this boat sank the 5,227-ton British Ashworth, 2,342-ton Norwegian Fagersten and 3,785-ton Norwegian Senta. During the daylight hours of 13 October U-221 maintained contact and called up U-599, U-216, U-607 and U-258, but these were driven off by Viscount, Potentilla and Eglantine, of which the last tackled U-258 with gunfire.

During the night of 13/14 October U-221 attacked once again while three escorts remained astern, sank the 5,929-ton US Susana and torpedoed the 12,398-ton British whale factory ship Southern Empress, which was later finished off and went down with a cargo that included 10 52-ton medium landing craft. A short time later Oberleutnant Wolf Jeschonnek’s U-607 and Oberleutnant Erich Lilienfeld’s U-661 attacked almost simultaneously and sank the 4,826-ton Greek Nellie and 3,672-ton Yugoslav Nikolina Matkovic respectively. U-607 was depth-charged and damaged by Viscount. As daylight approached, Kapitänleutnant Kurt Baberg’s U-618 sank the 5,791-ton British Empire Mersey. At about 12.00 on 14 October U-215 re-established contact, but before the return of darkness the escorts had been able to drive off U-661, U-258 and U-599, which had been located by HF/DF.

The 'Leopard' (i) wolfpack was meanwhile transiting from the ONS.136 convoy to the SC.104 convoy. In the night Montbretia drove off U-661, then U-607 was forced to dive before being depth-charged and damaged by Acanthus. Viscount located Lilienfeld’s U-661 on radar and delivered a high-speed ramming attack which sank the boat. On the same day U-615 was attacked and slightly damaged by a Liberator of No. 120 Squadron. Potentilla forced U-254 to dive and Eglantine then depth-charged and damaged the boat.

During the daylight hours of 15 October Fregattenkapitän Kurt Sturm U-410 sank the 7,154-ton British Fort St Nicholas, Fame and Acanthus managed to drive off U-258 and U-599, and in the afternoon Acanthus depth-charged U-442. A Liberator of No. 120 Squadron bombed U-615 and compelled U-437 to dive.

Contact with the convoy was re-established by U-258 only during the morning of 16 October, but the arrival of Liberator aircraft of No. 120 Squadron and Consolidated Catalina flying boats of the VP-84 squadron then drove off all the boats. At about 12.00 Römer’s U-353 was located on sonar by Fame as the boat tried to make a submerged attack: the U-boat was depth-charged and forced to the surface, where it was rammed and sunk. In the evening U-571, which has just arrived, approached the convoy, now escorted only by the four Norwegian corvettes, but was slightly damaged by Potentilla's gunfire and depth charges.

Before U-258 once again sighted the convoy in the morning of 16 October the 'Wotan' (ii) wolfpack was redirected to the nearby ON.137 convoy and the Canadian Escort Group C4, which had been reported by U-704.