ON convoys

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The ON convoys were a series of North Atlantic convoys which ran during the battle of the Atlantic in World War II.

They were Outbound, on the North Atlantic route, and were organized in July 1941 to replace the OA/OB series of outbound convoys that had run up to that point.

Previously, outbound convoys had departed from London (OA) via the Channel, or Liverpool (OB), past the south coast of Ireland, making rendezvous in the Western Approaches. From there they would continue west under the OB number, or go south, under a new OG (Outbound Gibraltar) number.

At this stage of the campaign, convoys would be escorted out of the Western Approaches only, dispersing in mid-Atlantic beyond the range of the U-boats, to proceed independently.

After the fall of France this became unworkable; all outbound traffic departed from Liverpool and was routed round the north coast of Ireland. Also as the range of the U-boats extended, so to did the length of conveyance, and the provision of escorts, until by the summer of 1941 ships were convoyed and escorted “end-around”.

To reflect these changes, all outbound north convoys were numbered in an ON series; ON 1 sailed in July 1941.

The ON convoys were organized into Fast (ie ships that could make 9-13 knots) and Slow (8 knots or less)and were designated ON(F) (or merely ON ) and ON(S), though they continued to be numbered in sequence.

This situation, which has proved confusing to modern historians, prevailed until Spring 1943 when a new series of ONS (Outbound North Slow) convoys was organized.

ONS 1 ran in March 1943; ON 171 was a fast convoy, as were all subsequent ON convoys.

The ON convoys were routed to the east coast of America, in ballast or with trade and export goods; until August 1942 most were routed to Halifax, though some sailed to New York, either direct or via the Cape Cod canal and the East River. After August they were routed direct to New York, with detachments to Canadian ports.

307 ON convoys sailed in total, between July 1941 and May 1945; one sailed in Fast and Slow sections and two others were cancelled.

14,864 ships sailed in them; 81 were lost to U-boats, and another 23 to marine accidents (though this figure does not include stragglers; throughout the battle of the Atlantic, the majority of casualties to U-boats were ships sailing independently, or had fallen out of convoys). Also, 10 warships on escort duty were also lost.

The ONS series was started in March 1943 and ran till the end of the campaign, though they were suspended in the summer of 1944 as escort groups were diverted to cover the Normandy landings.

There were 51 convoys in the ONS series altogether; 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 18 was the last major convoy battle in the campaign.

1,873 ships sailed in ONS convoys; of these, 19 were lost (around 1%).

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.

Notable battles around convoys of the various Outbound North series’ were:

• Convoy ON-154 included the last Q-ship operation by the Royal Navy.^[1] Loss of 486 lives with 14 ships during the "Christmas Convoy" of December 1942 caused re-evaluation of Canadian convoy escorts.^[2]

• 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 KM's autumn offensive after Black May.

[edit] Notes

[edit] References

• Dan van der Vat : The Atlantic Campaign (1988).ISBN 0 340 37751 8
• Arnold Hague : The Allied Convoy System 1939-1945 (2000). ISBN (Canada) 1 55125 033 0 . ISBN (UK) 1 86176 147 3
• Lenton, H.T. and 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). 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.