When leaving Halifax on 17 March: Canadian destroyer HMCS St. Croix (I 81) (Cdr H. Kingsley, RCN) and Canadian corvette HMCS Orillia (K 119) (T/LtCdr W.E.S. Briggs, RCNR) as western local escort until 18 March. British armed merchant cruiser HMS California (F 55) (Capt C.J. Pope, RAN) as ocean escort until 28 March.
Joined on 20 March: British battleship HMS King George V (41) (Capt W.R. Patterson, RN) and British submarine HMS Thunderbolt (N 25) (Lt C.B. Crouch, RN) until 28 March

Eastern local escort coming from convoy OB-302 and joining on 29 March: three British destroyers HMS Reading (G 71) (LtCdr D.V. Clift, RN), HMS Sabre (H 18) (Lt P.W. Gretton, DSC, RN) and HMS Venomous (D 75) (Cdr H.P. Henderson, RN), the British sloop HMS Wellington (L 65) (LtCdr W.F.R. Segrave, RN), three British corvettes HMS Alisma (K 185) (LtCdr M.G. Rose, RANVR), HMS Dianella (K 07) (T/Lt J.G. Rankin, RNR) and HMS Kingcup (K 33) (Lt R.A.D. Cambridge, RNR) and three British armed trawlers HMS Lady Elsa (FY 124) (T/Lt S.G. Phillips, RNVR), HMS Man o’ War (FY 104) (T/Lt W.W. Creber, RNR) and HMS Northern Dawn (FY 146) (Lt G.P.S. Lowe, RNVR)

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

On 17 Mar, 1941, the convoy HX-115 left Halifax with 32 ships of which two soon returned to harbor. As the German battleships Scharnhorst and Gneisenau were known to operate in the North Atlantic, the ocean escort was reinforced by HMS King George V and the submarine HMS Thunderbolt on 20 March. On 28 March, one merchant ship bound for Iceland left the convoy, followed by the armed merchant cruiser, the submarine and eventually the battleship, leaving the remaining 29 ships of convoy HX-115 without escort for the following night.

At 05.58 hours on 29 March, U-48 spotted the unescorted convoy south of Iceland in moderate weather and immediately attacked to use the few remaining hours of darkness left of the moonless night, firing six single torpedoes at six different targets from within the columns on the port side during the next hour and claiming the sinking of four ships, including the British tanker Athelprince and the British freighters Hylton and Masunda identified from distress signals. However, the torpedo data computer was out of order after the third attack, causing the torpedoes to miss their intended targets but sometimes hitting other ships beyond them. The attack was further hampered by an emergency turn to starboard, the defensive fire from several merchant ships and the ramming attempt of at least one freighter, the British Oakworth in station #13. In fact, only three ships had been hit by one torpedo each: Hylton, the ship of the vice commodore in station #21, Germanic in station #43 and Limbourg in station #23. None of the ships hit managed to send a distress signal, so the torpedo attacks were reported by nearby ships and some of their messages apparently misinterpreted by the German xB-Dienst.

After carrying out an emergency turn to port at dawn, the U-boat was spotted astern of the convoy and the commodore ordered to lay a smoke screen, while the ships at the end of the columns on the starboard side began shelling the enemy without obtaining any hits. Just after 08.00 hours, U-48 fired two single torpedoes at two ships from a great distance and claimed the sinking of a ship of 6000 grt after observing a hit on one of them, but this is not confirmed from Allied records. At 08.50 hours, the first warships of the eastern local escort arrived at the scene, prompting the U-boat to dive immediately because they had only two torpedoes remaining under deck which were not reloaded yet. Hylton and Germanic had been abandoned but were still afloat, so HMS Daniella with an inoperative ASDIC set was ordered to pick up the survivors screened by HMS Venomous and to check if the ships could be saved, but they were beyond salvage: Germanic sank about 12.30 hours and Hylton as scuttled by the destroyer with gunfire. In the meantime HMS Sabre searched for the attacker together with HMS Man o’ War and HMS Northern Dawn but failed to gain any contact and they left around noon to rejoin the convoy. U-48 surfaced shortly afterwards and chased the convoy for a short time until Schultze decided to operate against the now unescorted convoy OB-302 which had been reported by U-69 earlier that day.