The Arnold Hague database for the ON series of convoy: The OS series of convoy sailed from the UK to Freetown from July 1941 to May 1945. Vessels destined for South America or onward to the Cape would be detached south of the Canary Islands. From April 1943 onwards, the OS series sailed in conjunction with the KMS series which was detached off Gibraltar.
OS/ KMS STATUS
Convoys
187
Ship Entries
6,454
Escort Duties
1,426