'AT' (ii) was the designation of Allied military convoys (together with a numerical suffix) ferrying troops across the North Atlantic from the USA to the UK often in large liners converted as troopships, and as such reciprocals of the 'TA' series (January 1942/July 1945).

The AT convoy route was frequently plied by singleton liners, which relied on their high speed and considerable size rather than escorting warships for protection against the attentions of the U-boats.

The first of these convoys was AT.10 of 15/27 January 1942 with the 7,112-ton US Borinquen, 7,555-ton US Chateau Thierry, 12,600-ton US Delta, 22,281-ton British Strathaird and 6,338-ton US commissioned transport Munargo, escorted by 23 US warships in the form of the light fleet carrier Wasp, battleship Texas, heavy cruisers Quincy, Tuscaloosa and Wichita, and destroyers Charles F. Hughes, Eberle, Grayson, Gwin, Hilary P. Jones, Ingraham, Lansdale, Livermore, Ludlow, Mayrant, Meredith, Monssen, Roe, Rowan, Stack, Sterett, Trippe and Wainwright.

The last of the convoys was AT.223 of 26/31 July 1945 comprising only the 83,673-ton British liner Queen Elizabeth without escort.