Mid-ocean escort force
On the basis of experience during World War I, the Admiralty instituted trade convoys in United Kingdom coastal waters from September 1939.
Early German Type II submarines from bases in Germany were unable to operate effectively beyond European coastal waters.
HX 129 left Halifax on 27 May 1941 as the first convoy to receive escort for the entire trip.
[5] The Royal Canadian Navy continued to escort the SC convoys and their slower ON counterparts.
[7] The Gleaves-class destroyer Kearny was torpedoed while escorting Convoy SC 48 on 17 October 1941.
[8] Clemson-class destroyer Reuben James was torpedoed and sunk on 31 October 1941 while escorting Convoy HX 156.
[9] When the United States declared war, American escort groups typically contained five destroyers, although six United States Coast Guard Treasury-class cutters were included within the pool of ships rotating in and out of these escort groups.
[10] As the United States Navy struggled to find enough destroyers to meet escort needs for both the Pacific and the vulnerable Atlantic coastal shipping, the shorter great-circle route from Newfoundland to the British Isles was considered as a means of eliminating meeting point delays and reducing the number of destroyers required for escort of convoys between Canada and the United Kingdom.
Approximately one-third of the theoretical MOEF escort group strength of three destroyers and seven corvettes was unavailable at any given time.
[12] Half of the unavailable ships needed storm or battle damage repairs,[13] and the remainder were undergoing normal refit and training.
The Royal Navy continued to provide an eastern local escort force of naval trawlers in the Western Approaches while Canada continued to provide a western local escort force (WLEF) of corvettes, minesweepers, and short-range destroyers between Halifax Harbour and Newfoundland.
[15] Corvettes had adequate endurance for MOEF assignments, but the fuel economy of destroyers was poor at the speeds that convoys operated.
[17] Wickes-class destroyers were useful for the Canadian WLEF and the American Iceland shuttle; but lacked endurance to stay with a trade convoy for the full distance covered by the MOEF Escort Groups.
The Admiralty converted some V and W-class destroyers to long range escorts by removing the forward boiler and using the space for additional fuel tanks.
[18] Nineteen modern American destroyers left the Atlantic to escort the battleships New Mexico, Mississippi, Idaho, and North Carolina and the aircraft carriers Yorktown, Wasp, and Hornet to the Pacific.
Escort Groups A-4 and A-5 were redesignated B6 and B7, respectively, when the Royal Navy assigned F-class destroyers Fame and Firedrake as leaders.
[23] USCG Treasury-class cutters Spencer and Campbell assumed escort leader responsibility.
[24] The escort group was then redesignated C-5 under Canadian command after the USCG Treasury-class cutters were reassigned for conversion to amphibious force flagships.
[34] Flower-class corvettes Borage, Meadowsweet and Wallflower joined the group; and Venomous was replaced by the long-range W-class escort Watchman.
[36] Flower-class corvettes Campanula, Heather and Mignonette joined the group; and the low-endurance destroyers Leamington and Veteran were replaced by long-range V and W-class escorts Vanessa and Whitehall.
[36] The Royal Norwegian Navy-crewed Flower-class corvettes Andenes, Eglantine, Rose, Potentilla, and Montbretia from Escort Group A4, and the new leader F-class destroyer Fame were joined by the V-class Viscount (which had been reconstructed as a long range escort), the Town-class destroyer Ramsey, and the British Flower-class corvettes Kingcup and Vervain.
[44] The Flower-class corvette Loosestrife from Escort Group A-5, and the new leader F-class destroyer Firedrake were joined by the Town-class destroyers Chesterfield and Ripley and by the Flower-class corvettes Alisma, Coreopsis, Jonquil, Pink and Sunflower.
[56] Convoy ON 113 lost three ships torpedoed by U-552, U-607 and U-132 while Town-class destroyer St. Croix sank U-90.
[59] Convoy ON 115 lost two ships torpedoed by U-552 and U-553 while Skeena and Flower-class corvette Wetaskiwin sank U-588.
[31] Convoy SC 109 lost one ship torpedoed by U-43 and Saguenay was irreparably damaged when depth charges blew off its stern following a collision.
Destroyers replaced by new frigates were formed into mobile support groups able to move rapidly to convoys coming under attack.
[68] As the winter weather cleared, new Very Long Range Consolidated B-24 Liberator patrol bombers extended surveillance into the mid-Atlantic.
