The ON and later ONS convoys were a series of

North Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for ...

trade

convoy A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used ...

s running Outbound from the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

to North America during the Atlantic campaign of the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. 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

, all traffic outbound from Britain was organized into the OA and OB series, sailing from London via the

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

(OA) and from Liverpool via St Georges Channel (OB) into the

South-Western Approaches The Celtic Sea is the area of the Atlantic Ocean off the southern coast of Ireland bounded to the north by Saint George's Channel; other limits include the Bristol Channel, the English Channel, and the Bay of Biscay, as well as adjacent portion ...

. These would be escorted until beyond the range of

U-boat U-boats are Submarine#Military, naval submarines operated by Germany, including during the World War I, First and Second World Wars. The term is an Anglicization#Loanwords, anglicized form of the German word , a shortening of (), though the G ...

patrols before the ships dispersed to reach their destinations. After the

fall of France The Battle of France (; 10 May – 25 June 1940), also known as the Western Campaign (), the French Campaign (, ) and the Fall of France, during the Second World War was the German invasion of the Low Countries (Belgium, Luxembourg and the Net ...

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 Halifax Harbour is a large natural harbour on the Atlantic coast of Nova Scotia, Canada, located in the Halifax Regional Municipality. Halifax largely owes its existence to the harbour, being one of the largest and deepest ice-free natural har ...

. These convoys were sequentially numbered from ON 1 sailing on 26 July 1941 to ON 305 sailing on 27 May 1945. From August 1942, the Mid-Ocean Escort Force of British and Canadian ships (with a few

United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and Admiralty law, law enforcement military branch, service branch of the armed forces of the United States. It is one of the country's eight Uniformed services ...

cutters) delivered ON convoys to the

Royal Canadian Navy The Royal Canadian Navy (RCN; , ''MRC'') is the Navy, naval force of Canada. The navy is one of three environmental commands within the Canadian Armed Forces. As of February 2024, the RCN operates 12 s, 12 s, 4 s, 4 s, 8 s, and several auxiliary ...

Western Local Escort Force 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 (WOMP or WESTOMP) near Newfoundland where ships of the Mid ...

(WLEF) off Halifax; and the WLEF escorted most convoys from ON 125 through ON 301 to

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

. 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

warship A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as b ...

s on escort duty were also lost.

ONS convoys

Until April 1943, ships capable of speeds between were assigned to odd-numbered (fast) convoys—sometimes designated ON(F); while ships capable of speeds between 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. 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 The Normandy landings were the landing operations and associated airborne operations on 6 June 1944 of the Allies of World War II, Allied invasion of Normandy in Operation Overlord during the Second World War. Codenamed Operation Neptune and ...

. 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 Convoy ON 67 was a trade convoy of merchant ships during the Second World War. It was the 67th of the numbered series of ON convoys Outbound from the British Isles to North America. The ships departed from Liverpool on 14 February 1942 with ...

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 * Convoy ON 92 lost seven ships over a three-day period *

Convoy ON 122 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 join ...

was the first to illustrate the defensive value of HF/DF and type 271 centimeter-wavelength radar. *

Convoy ON 127 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 whe ...

was the only North Atlantic trade convoy of 1942 or 1943 where all U-boats deployed against the convoy launched torpedoes. * Convoy ON 144 demonstrated the ability of s equipped with type 271 centimetre-wavelength radar. *

Convoy ON 154 Convoy ON 154 (alternatively Convoy ON(S) 154 or Convoy ONS 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 convoy ...

Loss of 486 lives with 14 ships during the "Christmas Convoy" of December 1942 caused re-evaluation of Canadian convoy escorts.Milner 1985 pp. 3–4 *

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 G ...

. Attacked in late February, 1943, ON 166 lost 13 merchant ships and the

Convoy rescue ship During the Second World War, designated convoy rescue ships accompanied some Battle of the Atlantic (1940), Atlantic convoys to rescue survivors from ships that had been attacked. Rescue ships were typically small freighters with passenger accomm ...

''Stockport''. Three

s were destroyed and the

USCG The United States Coast Guard (USCG) is the maritime security, search and rescue, and law enforcement service branch of the armed forces of the United States. It is one of the country's eight uniformed services. The service is a maritime, mi ...

leading Escort Group A-3 was disabled. *

Convoy ONS 5 ONS 5 was the 5th of the numbered ONS series of Slow trade convoys Outbound from the British Isles to North America. The North Atlantic battle surrounding it in May 1943 is regarded as the turning point of the Battle of the Atlantic in World Wa ...

. 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 ONS 18 and ON 202 were North Atlantic convoys of the ONS/ON series which ran during the battle of the Atlantic in World War II. They were the subject of a major U-boat attack in September 1943, the first battle in the ''Kriegsmarine''s autumn ...

. 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 The (, ) was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official military branch, branche ...

'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

References

* * *

Dan van der Vat Daniel Francis Jeroen van der Vat (28 October 1939 – 9 May 2019) was a journalist, writer and military historian, with a focus on naval history. Born in Alkmaar, North Holland, Van der Vat grew up in the German- occupied Netherlands. He attended ...

. ''The Atlantic Campaign'' (1988). * * * * * {{World War II ON 0

ON convoys

ONS convoys

Notable battles around ON and ONS convoys

See also

Notes

References