(DD-252: dp. 1,190 1. 314' 5", b. 31'8", dr. 9'3", s. 35 k.cpl. 120; a. 4 4 ', 2 3", 12 21" tt., cl. Clemson)
McCook (DD-252) was laid down 10 September 1918 at the Bethlehem Shipbuilding Corp., Quincy, Mass.; launched 31 January 1919- sponsored by Mrs. Henry C. Dinger; and commissioned 30 April 1919, Lt. Comdr. G. B. Ashe, in command.
Following shakedown, McCook was assigned to Destroyer Force, Atlantic Fleet She operated along the east coast until decommissioning at Philadelphia 30 June 1922. She remained in the Atlantic Reserve Fleet until recommissioned 18 December 1930. The next year McCook was designated for exchange under the destroyers for bases agreement with Great Britain. Steaming to Halifax, she arrived 20 September 1940. Decommissioned on the 24th she was transferred to Great Britain on the same date, but due to manpower shortages in the Royal Navy, she was retransferred immediately to the Canadian Navy and commissioned as HMCS St. Croix ( I-81) .
Delayed by repairs necessitated by hurricane damage, on 14 March 1941 St. Croix assumed escort and patrol duties in Canadian waters. At the end of August she joined the Newfoundland Escort Force and plied between St. John's and ReykJavik. By May 1942 the force had been renamed the Mid-Ocean Escort Force and its range extended to Londonderry.
St. Croix scored her first kill when she sank U-90 on 24 July 1942, which, with other U-boats, had attacked her convoy, ON 113, on the 23d, sinking two merchantmen and damaging a third. On the return voyage, convoy ON 127 was attacked by 13 U-boats. Between 10 and 14 September 11 merchantmen and one destroyer was lost. Revenge came to St. Croix the following year. En route from Londonderry to Gibraltar on 4 March 1943 with convoy KMS 10, she assisted HMCS Shediac (K-100) in the sinking of U-87 some 200 miles off the Iberian coast.
With the addition of air escort to convoy defense in 1943, U-boat tolls in the North Atlantic diminished and many of the boats were withdrawn during the summer. In the fall, however, Germany began a new U-boat offensive. On I6 September, St. Croix, then on her first patrol with an offensive striking group in the Bay of Biscay, went to the aid of convoy ONS 18, followed by ON 202, both heavily beset by a wolfpack. The defense of' these convoys resulted in a long running battle with losses to both sides . The convoys lost three escorts and six merchantmen, while two other escorts were damaged. The wolfpack lost three U-boats.
St. Croix, taking three hits in the stern on the 20th, was the first escort to be sunk. HMS Polganthus (K-47) was sunk as she came up to screen HMS Itchen's rescue operations. Itchen (K-227), forced to retire that evening, returned the next morning and picked up 81 survivors from St. Croix and one from Polganthu,. The following day, 22 September, Itchen was torpedoed. Three men were rescued, two from Itchen, one from St. Croix.