Convoy ON 144 was a trade convoy of merchant ships during the Second World War. It was the 144th of the numbered series of ON convoys Outbound from the British Isles to North America. The ships departed Liverpool on 7 November 1942 and were joined on 8 November by Mid-Ocean Escort Force Group B-6 consisting of the Flower-class corvettes Vervain, Potentilla, Eglantine, Montbretia and Rose and the convoy rescue ship Perth. Group B-6 had sailed without the destroyers Fame and Viscount which had been damaged in the battle for eastbound convoy SC 104. The United States Coast Guard cutters Bibb, Duane, and Ingham accompanied the convoy from the Western Approaches with ships that detached for Iceland on 15 November.
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, of the 180 trans-Atlantic convoys sailing from the end of July 1942 until the end of April 1943, only 20 percent lost ships to U-boat attack.
The Norwegian-manned corvettes of escort group B-6 fought three of these convoy battles in sequential voyages with convoys SC 104, ON 144, and HX 217.
15 November
After rendezvousing with convoys to and from Iceland, Convoy ON 144 was discovered and shadowed by U-521.
16 November
When initial attempts to summon additional U-boats to the convoy were unsuccessful, U-521 was granted permission to attack, and missed with a salvo of six torpedoes. Rose unsuccessfully counterattacked with depth charges.
17 November
U-184, U-262 and U-264 found the convoy and launched a simultaneous attack after sunset. U-262 missed with three torpedoes. U-264 sank the 6,696-ton Greek freighter Mount Taurus, and U-184 sank the 3,192-ton British freighter Widestone.
18 November
U-624, U-522, U-521, U-224, U-383, U-454 and U-753 launched torpedoes in the pre-dawn hours. U-624 sank the 5,344-ton British tanker President Sergent and the 4,732-ton American freighter Parismina and damaged the 5,432-ton American freighter Yaka which was later sunk by U-522. The Type 271 centimeter-wavelength radar-equipped corvettes counterattacked, and U-184 was sunk by one of those attacks. Montbretia was torpedoed by U-262 and sank while still moving forward.
19 November
The U-boats had broken off the engagement by the time the four surviving corvettes were reinforced by the destroyers HMS Firedrake and USS Badger, and the Western Local Escort Force assumed responsibility for the convoy on 20 November.