Convoy ONS 5

Convoy ONS 5
Part of World War II
Date 29 April-6 May 1943 Location North Atlantic Result British Victory
Belligerents
Nazi Germany	United Kingdom Canada
Commanders and leaders
Admiral Karl Dönitz	Convoy Comm: JK Brook RNR Escort B7: Cdr Peter Gretton
Strength
Star 16 U-Boats Finke 27 U-boats	42 ships 7 escorts
Casualties and losses
6 U-boats sunk 7 U-boats damaged	13 ships sunk (63,000 gross register tons (GRT))

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 War II. The battle ebbed and flowed over a period of a week, and involved more than 50 Allied ships and their escorts, and over 30 U-boats. It saw heavy losses on both sides. However it was almost the last Allied convoy to do so, while losses inflicted on attacking U-boats and U-boat groups became a besetting feature of the campaign; As such it is seen as the point when the tactical and strategic advantage passed to the Allies, and ushered in the period known to Nazi Germany's Kriegsmarine as Black May.

ONS 5 consisted of 43 ships bound from Liverpool to Halifax. The ships were either in ballast or carrying trade and export goods. The convoy departed Liverpool on 21 April 1943, and would arrive in Halifax three weeks later on 12 May. It was under the command of JK Brook RNR as Convoy Commodore, traveling in the Norwegian freighter Rena. The escort was provided by Mid-Ocean Escort Force group B7, 7 warships under Captain Peter Gretton, in the destroyer Duncan. Also in the group were the destroyer Vidette, frigate Tay, and corvettes Sunflower, Snowflake, Loosestrife, and Pink. The group also contained 2 trawlers, Northern Gem and Northern Spray as rescue ships, and the fleet oiler British Lady for mid-ocean re-fuelling. The convoy was joined by other escort vessels as the battle progressed.

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