[4] After trials and working up, Arbutus joined Western Approaches Command and was assigned to the 6th Escort Group, led by J. M. Rowland in HMS Wolverine for trade protection.

In this role she was engaged in all the duties performed by escort ships; protecting convoys, searching for and attacking U-boats, and rescuing survivors.

Over the next 14 months Arbutus escorted 26 convoys on the Atlantic routes, helping to bring over 750 ships to safety, though a number were lost in various incidents.

This was the first such instance of a U-boat boarding in World War II; the exploit was repeated the following month when U-110 was captured by ships of the 3rd Escort Group.

The U-boat sent a sighting report and commenced shadowing, but the transmission was DFed and escorts Chelsea and Arbutus ran down the bearing to attack.