1939 1940 1941 1942 1943 1944 1945 SC 7 was the code name for a large Allied convoy in the Second World War comprising 35 merchant ships and six escorts, which sailed eastbound from Sydney, Nova Scotia, for Liverpool and other British ports on 5 October 1940.

The disaster demonstrated the potency of wolfpacks (attacking in numbers) and the inadequacy of British anti-submarine operations.

The slow Convoy SC 7 left Sydney, Nova Scotia on 5 October 1940 bound for Liverpool and other British ports.

The largest ship in the convoy was the 9,512 GRT oil tanker MV Languedoc, belonging to the Admiralty, which was bound for the Clyde with fuel for the Royal Navy.

The convoy commodore, Vice Admiral Lachlan MacKinnon, a retired naval officer who had volunteered for war service, sailed in SS Assyrian, a British ship of 2,962 GRT.

Many of the merchant ship captains were resentful at having to sail in convoy and would have preferred to take their chances on their own, rather than risk such a slow crossing with a weak escort.

They were often uncooperative; at one point early in the voyage Scarborough's captain was shocked to find a Greek merchant ship in the convoy travelling at night with her lights on.

On 17 October, as the convoy entered the Western Approaches, Scarborough was joined by the sloop Fowey and the new corvette Bluebell.

The attack was coordinated from Lorient by Admiral Karl Dönitz the Befehlshaber der U-Boote (Commander, U-boats) and his staff.

Also among the casualties was the commodore's ship, Assyrian, which went down with 17 crew (Mackinnon was rescued after a long immersion in the chilly waters).

Later that afternoon Leith met Heartsease, still escorting the damaged Carsbreck; together they headed for Gourock, Renfrewshire, collecting two more stragglers on the way.

[5] In the German semi-official history, Germany and the Second World War (2015), Bernd Stegemann wrote that the U-boats had their best success per-day-at-sea in October 1940.

During the winter of 1940–1941 the U-boats had less success due to the seasonal weather, the British–US destroyers-for-bases deal, the arrival of the first corvettes, the addition of radar sets and radio-telephones to British destroyers and the slow increase in the number of Coastal Command aircraft.