ON/ONS convoys

Last updated October 27, 2024

The ON and later ONS convoys were a series of North Atlantic trade convoys running Outbound from the British Isles to North America during the Atlantic campaign of the Second World War. The ON convoys replaced the earlier OA/OB series of outbound convoys in July 1941 and ran until the end of the campaign in May 1945. They were organized as alternating fast and slow convoys until March 1943, when the ONS series was begun to take over the slow trans-Atlantic traffic, after which all in the ON series were fast.

ON convoys

From 7 September 1939, shortly after the outbreak of the Second World War, all traffic outbound from Britain was organized into the OA and OB series, sailing from London via the English Channel (OA) and from Liverpool via St Georges Channel (OB) into the South-Western Approaches. These would be escorted until beyond the range of U-boat patrols before the ships dispersed to reach their destinations. After the fall of France in June 1940 these were successively reorganized as German aircraft, submarines and surface ships reached further and further into the Atlantic, until ships formerly assigned to OA/OB convoys were formed into ON convoys sailing from Liverpool via the North Channel and escorted all the way to Halifax Harbour. These convoys were sequentially numbered from ON 1 sailing on 26 July 1941 to ON 305 sailing on 27 May 1945.^[1]

From August 1942, the Mid-Ocean Escort Force of British and Canadian ships (with a few United States Coast Guard cutters) delivered ON convoys to the Royal Canadian Navy Western Local Escort Force (WLEF) off Halifax; and the WLEF escorted most convoys from ON 125 through ON 301 to New York City.^[2]

Most ships in ON convoys were in ballast, although some carried coal or other export goods. A total of 14,864 ships sailed in 307 ON convoys. One ON convoy sailed in Fast and Slow sections and two others were cancelled. U-boats sank 81 of these ships, and another 23 were lost to marine accidents. These figures do not include stragglers; although the majority of casualties to U-boats were ships that had fallen out of convoys or were sailing independently. Ten warships on escort duty were also lost.

ONS convoys

Until April 1943, ships capable of speeds between 9 and 13 knots (17 and 24 km/h; 10 and 15 mph) were assigned to odd-numbered (fast) convoys—sometimes designated ON(F); while ships capable of speeds between 6 and 9 knots (11 and 17 km/h; 6.9 and 10.4 mph) were assigned to even-numbered (slow) convoys—sometimes designated ON(S) or (ambiguously) ONS. This situation, which has proved confusing to modern historians, prevailed until a new and separate series of ONS (Outbound North Slow) convoys was organised. These convoys were sequentially numbered from ONS 1 sailing on 4 April 1943 to ONS 51 sailing on 21 May 1945.^[3] ON 171 was a fast convoy, as were all subsequent ON convoys. The ONS series were suspended in the summer of 1944 as escort groups were diverted to cover the Normandy landings. A total of 1873 ships sailed in 51 ONS convoys. Only 5 of these were attacked (around 10%), though two of these battles were of major significance; ONS 5 is regarded as the turning point of the campaign, while ONS 20 was the last major convoy battle in the campaign. Nineteen ships were lost (around 1 per cent) from ONS convoys.

Notable battles around ON and ONS convoys

The Outbound Northern convoys saw some of the major convoy battles of the Atlantic campaign; of the 40 convoys which lost 6 or more ships, 8 were in the ON series (of which 5 were Slow, and 3 were Fast) and one was in the ONS series.

Convoy ON 67 was one of the few North Atlantic trade convoy of early 1942 to be attacked by multiple U-boats. Eight ships were sunk, and one U-boat damaged, over a four day battle^[4]
Convoy ON 92 lost seven ships over a three-day period
Convoy ON 122 was the first to illustrate the defensive value of HF/DF and type 271 centimeter-wavelength radar.^[5]
Convoy ON 127 was the only North Atlantic trade convoy of 1942 or 1943 where all U-boats deployed against the convoy launched torpedoes.^[6]
Convoy ON 144 demonstrated the ability of Flower-class corvettes equipped with type 271 centimetre-wavelength radar.^[7]
Convoy ON 154 Loss of 486 lives with 14 ships during the "Christmas Convoy" of December 1942 caused re-evaluation of Canadian convoy escorts.^[8]
Convoy ON 166 . Attacked in late February, 1943, ON 166 lost 13 merchant ships and the Convoy rescue ship Stockport. Three U-boats were destroyed and the USCG Treasury-class cutter leading Escort Group A-3 was disabled.
Convoy ONS 5 . Attacked in April–May 1943, ONS 5 saw the loss of 12 ships, and the destruction of 6 U-boats, in a week-long series of actions. It ushered in the period known as Black May and is widely regarded as the turning point in the Atlantic campaign.
Convoys ONS 18/ON 202 . Attacked in September 1943, these two convoys saw the loss of 6 ships and 3 escorts, for the destruction of 3 U-boats, in the first battle of the Kriegsmarine's autumn offensive after Black May.
Convoy ONS 19 : In September 1943 the forces escorting this ONS 19 destroyed three U-boats encountered in Mid-Atlantic. The convoy was not attacked and no ships were lost.
Convoys ONS 20/ON 206 : Attacked in October 1943, six U-boats were destroyed while one merchant ship was sunk

Notes

↑ Hague 2000 pp. 157–160
↑ Hague 2000 pp. 158–160
↑ Hague 2000 pp. 163–164
↑ Blair (1996) p. 510
↑ Milner pp. 148–150
↑ Rohwer & Hummelchen 1992 p. 161
↑ Blair (1998) pp. 118–120
↑ Milner 1985 pp. 3–4

Related Research Articles

HX convoys were transatlantic convoys in the North Atlantic during the First World War and in the Battle of the Atlantic in the Second World War. HX convoys sailed eastwards from Halifax, Nova Scotia in Canada, to Liverpool and other ports in Britain. They were joined the BHX convoys from Bermuda en route. After the United States entered the war, HX convoys began at New York.

This is a timeline for the Battle of the Atlantic (1939–1945) in World War II.

Escort Group B2 was a convoy escort British formation of the Royal Navy which saw action during the Second World War, principally in the Battle of the Atlantic. The group was under the command of Cdr Donald Macintyre, one of Britain's most successful anti-submarine warfare commanders.

HX 79 was an Allied convoy in the North Atlantic of the HX series, which sailed east from Halifax, Nova Scotia. The convoy took place during the Battle of the Atlantic in the Second World War. One ship dropped out and returned to port, leaving 49 to cross the Atlantic for Liverpool. Two armed merchant cruisers and a submarine escorted the convoy to protect it from German commerce raiders.

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 Treasury-class cutters Campbell and Spencer and the Flower-class corvettes Dianthus, Chilliwack, Rosthern, Trillium and Dauphin.

Convoy SC 94 was the 94th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island, Nova Scotia, to Liverpool. The ships departed Sydney on 31 July 1942 and were met by Mid-Ocean Escort Force Group C-1.

Convoy ON 154 was a North Atlantic convoy of the ON convoys which ran during the battle of the Atlantic in the Second World War. It was the 154th of the numbered series of merchant ship convoys Outbound from the British Isles to North America. It came under attack in December 1942 and lost 13 of its 50 freighters; one U-boat was sunk.

Convoy SC 104 was the 104th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island to Liverpool. During October 1942, a U-boat wolf pack sank eight ships from the convoy. The convoy escorts sank two of the attacking submarines.

Convoy ON 127 was a trade convoy of merchant ships during the second World War. It was the 127th of the numbered series of ON convoys Outbound from the British Isles to North America and the only North Atlantic trade convoy of 1942 or 1943 where all U-boats deployed against the convoy launched torpedoes. The ships departed Liverpool on 4 September 1942 and were met at noon on 5 September by the Royal Canadian Navy Mid-Ocean Escort Force Group C-4 consisting of the River-class destroyer Ottawa and the Town-class destroyer St. Croix with the Flower-class corvettes Amherst, Arvida, Sherbrooke, and Celandine. St. Croix's commanding officer, acting Lieutenant Commander A. H. "Dobby" Dobson RCNR, was the senior officer of the escort group. The Canadian ships carried type 286 meter-wavelength radar but none of their sets were operational. Celandine carried Type 271 centimeter-wavelength radar. None of the ships carried HF/DF high-frequency direction finding sets.

<span class="mw-page-title-main">Western Local Escort Force</span> World War II-era escort group in the Royal Canadian Navy

Western Local Escort Force (WLEF) referred to the organization of anti-submarine escorts for World War II trade convoys from North American port cities to the Western Ocean Meeting Point near Newfoundland where ships of the Mid-Ocean Escort Force (MOEF) assumed responsibility for safely delivering the convoys to the British Isles.

Convoy HX 90 was a North Atlantic convoy of the HX series in the Second World War which ran during the Battle of the Atlantic in both world wars.

Convoy HX 212 was the 212th of the numbered series of World War II HX convoys of merchant ships from HalifaX to Liverpool. The ships departed New York City on 18 October 1942 and were met on 23 October by Mid-Ocean Escort Force Group A-3 consisting of the United States Coast Guard Treasury-class cutter USCGC Campbell, the destroyer Badger and the Flower-class corvettes Dianthus, Rosthern, Trillium, Dauphin, Alberni, Summerside and Ville de Quebec. The first five escorts had worked together previously, but the last three corvettes were attached to the convoy only for passage to the eastern Atlantic in preparation for assignments on Operation Torch. Summerside was the only escort equipped with modern Type 271 centimeter-wavelength radar.

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.

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 Escort Group B6 of the Mid-Ocean Escort Force.

Convoy HX 65 was a North Atlantic convoy of the HX series which ran during the battle of the Atlantic in World War II. It was the 65th of the numbered series of merchant convoys run by the Allies from Halifax to Liverpool. The convoy was attacked by German U-boats and aircraft, losing eight of its 51 ships sunk and a further three damaged. One U-boat was damaged.

Convoy ON 92 was a trade convoy of merchant ships during the Second World War. It was the 92nd of the numbered series of ON convoys Outbound from the British Isles to North America. The ships departed from Liverpool on 6 May 1942 and were joined on 7 May by Mid-Ocean Escort Force Group A-3.

Convoy HX 47 was a North Atlantic convoy of the HX series which ran during the battle of the Atlantic in World War II. It was the 47th of the numbered series of merchant convoys run by the Allies from Halifax to Liverpool. The convoy was attacked by German U-boats and lost three of its 58 ships.

SL convoys were a numbered series of North Atlantic trade convoys during the Second World War. Merchant ships carrying commodities bound to the British Isles from South America, Africa, and the Indian Ocean traveled independently to Freetown, Sierra Leone to be convoyed for the last leg of their voyage to Liverpool.

The Gibraltar convoys of World War II were oceangoing trade convoys of merchant ships sailing between Gibraltar and the United Kingdom. Gibraltar convoy routes crossed U-boat transit routes from French Atlantic ports and were within range of Axis maritime patrol aircraft making these convoys vulnerable to observation and interception by bombers, submarines, and surface warships during the Battle of the Atlantic. OG convoys brought supplies from the United Kingdom to Gibraltar from September 1939 until September 1942. Beginning with Operation Torch, OG convoys were replaced by KM convoys transporting military personnel and supplies from the United Kingdom to and past Gibraltar into the Mediterranean Sea. HG convoys brought food, raw materials, and later empty ships from Gibraltar to the United Kingdom from September 1939 until September 1942. After Operation Torch, HG convoys were replaced by MK convoys returning mostly empty ships from the Mediterranean to the United Kingdom. KM and MK convoys ended in 1945.

Convoy HX 49 was a North Atlantic convoy of the HX series which ran during the Battle of the Atlantic in World War II. It was the 49th of the numbered series of merchant convoys run by the Allies from Halifax to Liverpool. The convoy was attacked by German U-boats, losing three of its 50 ships sunk. Another ship was lost after dispersal.

References

Blair, Clay (1996). Hitler's U-Boat War The Hunters 1939–1942. Random House. ISBN 0-394-58839-8.
Blair, Clay (1998). Hitler's U-Boat War: The Hunted 1942–1945. Random House. ISBN 0-679-45742-9.
Dan van der Vat. The Atlantic Campaign (1988). ISBN 0-340-37751-8
Hague, Arnold (2000). The Allied Convoy System 1939–1945, Its Organisation, Defence and Operation. London: Chatham. ISBN 1-86176-147-3.
Lenton, H.T. & Colledge, J.J. (1968). British and Dominion Warships of World War Two. Doubleday and Company.
Milner, Marc (1985). North Atlantic Run. Naval Institute Press. ISBN 0-87021-450-0.
Morison, Samuel Eliot (1975). The Battle of the Atlantic 1939–1943. History of United States Naval Operations in World War II. Vol. I. Boston, MA: Little, Brown. OCLC 7395406.
Rohwer, J. & Hummelchen, G. (1992). Chronology of the War at Sea 1939–1945. Naval Institute Press. ISBN 1-55750-105-X.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[1] Hague 2000 pp. 157–160

[2] Hague 2000 pp. 158–160

[3] Hague 2000 pp. 163–164

[4] Blair (1996) p. 510

[5] Milner pp. 148–150

[6] Rohwer & Hummelchen 1992 p. 161

[7] Blair (1998) pp. 118–120

[8] Milner 1985 pp. 3–4

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]