Convoy ON 166
Convoy ON 166 was the 166th of the numbered ON series of merchant ship convoys Outbound from the British Isles to North America. Sixty-three ships departed Liverpool 11 February 1943 and were met the following day by Mid-Ocean Escort Force Group A-3 consisting of the s and and the s , , , and . Background. As western Atlantic coastal convoys brought an end to the second happy time, Admiral Karl Dönitz, the "Befehlshaber der U-Boote" ("BdU") or commander in chief of U-Boats, shifted focus to the mid-Atlantic to avoid aircraft patrols. Although convoy routing was  less predictable in the mid-ocean, Dönitz anticipated that the increased numbers of U-boats being produced would be able to effectively search for convoys with the advantage of intelligence gained through "B-Dienst" decryption of British Naval Cypher Number 3. However, only 20 percent of the 180 trans-Atlantic convoys sailing from the end of July 1942 until the end of April 1943 lost ships to U-boat attack. 21 February. On 20 February sighted the convoy scattered by sailing eight days in a northwesterly gale. torpedoed the straggling Norwegian "Stigstad" on the morning of 21 February. was sunk  by a No. 120 Squadron RAF B-24 Liberator that afternoon, and "Campbell" attacked a U-boat that evening. Postwar analysis concluded that "Campbell" sank , but more recent re-evaluation indicates the attack may have destroyed . 22 February. torpedoed the British "Empire Redshank" and American "Chattanooga City" and "Expositor" after sunset 22 February, but was damaged by depth charges from the recently arrived "Burza". "Campbell" was disabled in a collision with "U-606". Twelve men were rescued from the crew of the sinking U-boat. "Burza" left the convoy to tow "Campbell" back to port. The convoy rescue ship "Stockport" was sunk  by "U-604" while returning to the convoy after rescuing men from the three ships torpedoed by "U-606". 23 February. torpedoed the Panamanian "Winkler" at 0420 and Norwegian "Glittre" at 0425. torpedoed the American "Hastings" about 0430 and British "Eulima" at 0458 on 23 February. "Spencer", "Rosthern" and "Chilliwack" remained with the convoy and "Dianthus" left to refuel. 24 February. torpedoed the Norwegian "Ingria" at 0520 before dawn on 24 February. torpedoed the straggling American Liberty ship "Jonathan Sturges". 25 February. "U-628" hit the British "Manchester Merchant" with two torpedoes on the starboard side at 0527 before dawn 25 February. Aftermath . The U-boats discontinued the attack on 26 February. The surviving ships in the convoy were joined by from Halifax, Nova Scotia on 28 February with escorts , and . They reached New York City on 3 March 1943.