During the voyage JW 56A was attacked by a German U-boat force; three ships were sunk and one of the escorts damaged in the operation.
Close escort was provided by a force led by Inconstant and two corvettes, with two more destroyers joining later.
A cruiser cover force comprising Kent (R.Adm AFE Palliser), Berwick and Bermuda also followed the convoy, to guard against attack by surface units.
JW 56A was opposed by a U-boat force of 10 boats in a patrol line, code-named Isengrim, in the Norwegian Sea.
Despite search patrols by German aircraft the convoy was not found in the prevailing gloom of the polar night, but on 25 January JW 56A passed the northernmost U-boat of the patrol line, U-739, which broadcast an alert and commenced shadowing.