Convoy ON 166

As western Atlantic coastal convoys brought an end to the Germans' "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 sank a U-boat that evening. Postwar analysis concluded that Campbell sank , but later re-evaluation indicated that the attack may have destroyed . torpedoed the British Empire Trader at 2032 and the Norwegian NT Nielsen Alonso at 0153 on the night of February 21–22. Both ships were hit by a single torpedo on the port side, flooding the forward hold, and boiler room, respectively. from the following convoy ONS 167 was ordered to reinforce the convoy escort. ==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. ==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. ==Ships in convoy==