On 1 July she sailed with the Ranger group for the coast of West Africa, where the carrier flew off Army aircraft for the burgeoning base at Accra.

Returning to Norfolk on 5 August, Forrest served in training operations, submarine searches, and coastal escort duty until 21 October, when she arrived at Bermuda to join the Ranger group for the invasion of North Africa.

Between 2 December 1942 and 27 March 1943, Forrest twice crossed the Atlantic screening Ranger to an ocean launching point off Casablanca as well as serving on coastal and Gulf of Mexico escort duty.

After training in Casco Bay, Maine, she joined the Ranger group for patrol duty out of Argentia, Newfoundland, between 17 May and 24 July, then replenished at Boston for the crossing to Scapa Flow, Orkney Islands.

From this base of the British Home Fleet, the Ranger group patrolled in search of German naval forces, and on 4 October struck with great success at the shipping and shore installations at Bodø, Norway.

In October she sailed south to join the escort for a British carrier returning from the Mediterranean to Scapa Flow, and in November sortied in a combined task force to patrol the northwest coast of Norway covering the passage of a convoy to Russia.

Forrest sailed from Norfolk 20 April for Northern Ireland, and took up escort duties around the British Isles as men and ships were concentrated for the Normandy invasion.

For the next two months, she escorted convoys from Palermo, Naples, Ajaccio, and Oran to the southern coast of France, guarding the men and supplies which made the push northward possible.