Convoy ON 122
|Convoy ON 122|
|Part of Battle of the Atlantic|
| United Kingdom
|Commanders and leaders|
|CAPT S.N. White RNR
LCDR J.V. Waterhouse RN
|Admiral Karl Dönitz|
|Casualties and losses|
|4 freighters sunk (17,235 GRT)
Convoy ON 122 was a trade convoy of merchant ships during the second World War. It was the 122nd of the numbered series of ON convoys Outbound from the British Isles to North America. The ships departed Liverpool on 15 August 1942 and were joined on 17 August by Mid-Ocean Escort Force Group B-6 consisting of V and W class destroyer Viscount with the Norwegian-manned Flower class corvettes Potentilla, Eglantine, Montbretia, and Acanthus and the Convoy rescue ship Stockport.
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 the area 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.
U-135 discovered and reported the convoy on 22 August while patrolling a formerly assigned station after having missed the signal to change position. The initial report caused some confusion because of the unexpected position and a coding error, but after U-135 sent two clarifying messages while shadowing the convoy, the wolf pack Lohs was ordered to converge on the convoy.
While the Norwegian corvettes investigated HF/DF bearings provided by Viscount and Stockport on 23 August, Viscount conserved fuel by declining to engage in long daylight stern chases with U-boats. Viscount and Potentilla attacked HF/DF contacts more aggressively through the hours of darkness, but were satisfied by simply forcing the U-boats to submerge rather than conducting sustained depth charge attacks.
Visibility was reduced to 7,000 yards with patchy squalls under overcast skies on 24 August. As dusk approached, the escort had located only four of the nine U-boats in contact with the convoy. The convoy's course was altered to 267° at 2300Z. U-605 torpedoed Katvaldis and Sheaf Mount on the starboard side of the convoy an hour after the course alteration. Viscount obtained a RADAR contact and forced the submarine to submerge. As Viscount was dropping depth charges, U-176 and U-438 entered the front of the convoy to torpedo Trolla and Empire Breeze.
The convoy escorts effectively intercepted attacks through the pre-dawn hours of 25 August. The calm sea conditions were favourable for the Type 271 centimeter-wavelength RADAR with which all the escorts were equipped, and prompt counter-attacks prevented the U-boats from reaching torpedo launch positions. A depth charge attack by Eglantine holed the conning tower of U-605. U-135, U-174 and U-438 were also damaged by depth charges. The shadowing U-boats lost contact after the convoy entered heavy fog after daybreak on 25 August, and discontinued pursuit on 26 August. U-256 was under repair for more than a year after being bombed in the Bay of Biscay on 31 August following depth charge damage from Viscount and Potentilla. U-438 aided U-256 reaching port, and U-174 refueled three Lohs U-boats before returning to France to repair damage. U-705 suffered several casualties when hit by gunfire from the convoy escorts; and was sunk in the Bay of Biscay by Armstrong Whitworth Whitleys of No. 77 Squadron RAF on 3 September.
Ships in convoy 
|Amberton (1928)||5,377 gross register tons (GRT)||destination Halifax|
|Athelprince (1926)||8,782 GRT||carried convoy commodore CAPT S.N. White RNR|
|Atland (1910)||5,203 GRT||coal||destination Saint John|
|Baron Herries (1940)||4,574 GRT||destination New York City|
|City of Lancaster (1924)||3,041 GRT||general cargo||destination New York City|
|Empire Breeze (1941)||1||7,457 GRT||(in ballast)||sunk by U-176 or U-438|
|Empire Chamois (1918)||5,684 GRT||destination New York City|
|Empire Wagtail (1919)||4,893 GRT||destination New York City|
|Fintra (1918)||2,089 GRT||destination Saint John|
|Gloxinia (1920)||3,336 GRT||destination New York City|
|Inger Elizabeth (1920)||2,166 GRT||coal||destination Halifax|
|Inger Toft (1920)||2,190 GRT||destination Sydney|
|Ingerfire (1905)||3,835 GRT||coal||destination Sydney|
|Ingman (1907)||3,169 GRT||destination Sydney|
|Isobel (1929)||1,515 GRT||destination Halifax|
|Jan (1920)||1,946 GRT||destination Herring Cove, Nova Scotia|
|Katvaldis (1907)||3||3,163 GRT||(in ballast)||sunk by U-605|
|Kolsnaren (1923)||2,465 GRT||destination New York City|
|Lifland (1920)||2,254 GRT||destination Montreal|
|Mariposa (1914)||3,807 GRT||destination New York City|
|Merchant Royal (1928)||5,008 GRT||destination Boston|
|Modlin (1906)||3,569 GRT||destination Halifax|
|Parismina (1908)||4,732 GRT||destination Boston|
|Ramava (1900)||2,141 GRT||destination Sydney|
|Rio Branco (1924)||3,210 GRT||destination Sydney|
|Rolf Jarl (1920)||1,917 GRT||coal||destination Halifax|
|Sheaf Mount (1924)||31||5,017 GRT||(in ballast)||sunk by U-605|
|Silverelm (1924)||4,351 GRT||general cargo||destination New York City|
|Sirehei (1907)||3,888 GRT||destination Sydney|
|Souliotis (1917)||4,299 GRT||destination Halifax|
|Stad Arnhem (1920)||3,819 GRT||destination New York City|
|Start Point (1919)||5,293 GRT||destination Botwood|
|Stockport (1911)||1,583 GRT||convoy rescue ship|
|Tenax (1925)||3,846 GRT||destination Sydney|
|Trolla (1923)||5||1,598 GRT||(in ballast)||sunk by U-438|
|Van de Velde (1919)||6,389 GRT||general cargo||destination New York City|
- Rohwer & Hummelchen p.157
- Hague pp.158&161
- "ON convoys". Andrew Hague Convoy Database. Retrieved 2012-09-19.
- Milner pp.148-150
- Tarrant p.108
- Hague pp.132, 137-138, 161-162, 164, 181
- Blair pp.662&663
- Blair, Clay (1996). Hitler's U-Boat War: The Hunters 1939-1942. Random House. ISBN 0-394-58839-8.
- Hague, Arnold (2000). The Allied Convoy System 1939-1945. Naval Institute Press. ISBN 1-55750-019-3.
- Milner, Marc (1985). North Atlantic Run. Naval Institute Press. ISBN 0-87021-450-0.
- Morison, Samuel Eliot (1975). History of United States Naval Operations in World War II, Volume I The Battle of the Atlantic 1939-1943. Little, Brown and Company.
- Rohwer, J. and Hummelchen, G. (1992). Chronology of the War at Sea 1939-1945. Naval Institute Press. ISBN 1-55750-105-X.
- Tarrant, V.E. (1989). The U-Boat Offensive 1914-1945. Arms and Armour. ISBN 1-85409-520-X.