ON Convoys - History

History

From 7 September 1939, shortly after the outbreak of World War II, OB convoys sailed from Liverpool south through St George's Channel to the open Atlantic. Off Land's End the convoy would be joined by an OA convoy from London on the River Thames via the English Channel. The combined OA/OB convoys were escorted for about four days to get beyond the range of U-boat patrols before the ships dispersed to reach their individual destinations. After the fall of France in June 1940, OA and OB convoys sailed north to join in the Western Approaches. As German aircraft, submarines, and surface ships reached further into the Atlantic, 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.

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.

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.