Since June 1939 used as troopship.
On 4 September 1939 the passenger ship Montrose of the Canadian Pacific Steamships Ltd, Montreal was requisitioned by the Admiralty and converted to the armed merchant cruiser HMS Forfar. Conversion was completed on 6 November 1939.

Displacement: 16402 BRT
Armament: 8x 152mm, 2x 76mm
Speed: 17 knots

Career:
November 39 - October 40: Northern Patrol
November 40 - December 40: Northern and Western Patrol

On 2 December 1940 HMS Forfar (Capt. Norman Arthur Cyril Hardy, RN) was torpedoed and sunk by the German submarine U-99 after she had just left the convoy HX-90 bound for OB-251 about 500 nautical miles west of Ireland in position 54º35'N, 18º18'W. The master, 35 officers and 136 naval ratings were lost. Three officers and 18 naval ratings were rescued by the Canadian destroyer HMCS St. Laurent (Cdr. H.G. De Wolf, RCN), the British destroyer HMS Viscount (Lt.Cdr. M.S. Townsend, OBE, DSC, RN) and the British merchant Dursley and landed at Oban.

Hit by U-boat
Sunk on 2 Dec 1940 by U-99 (Kretschmer).