OS and OS/KMS Convoy Series


This site is a database of mercantile vessels that sailed in the OS and OS/KMS convoy series. It holds data for convoys OS.1 - OS.131/KMS.105 where records exist and details nearly 5,000 individual ship movements. Please read the notes before using the database. For each convoy, vessels are listed in alphabetical order but should you wish to reconstruct the 'Cruising Order' to show the disposition of the ships, you may download a blank form here (print the page in landscape mode) and enter the ships' names according to their pendant numbers. For an example of a complete Cruising Order (Form A1), click here.

The OS series of convoy catered for vessels entering the South Atlantic and carried vessels from UK ports to the collection point of Freetown in Sierra Leone. Vessels sailing to South America or onward to the Cape would be detached from convoy at suitable points. Prior to OS.52/KMS.21 (when the Mediterranean was opened) the OS series also included vessels sailing to India - subsequently they sailed in the KMS section.

Although the complementary SL convoy series, from Freetown to the UK, had been sailing since September 1939, the OS series only began in July 1941, by which time some forty SL convoys had been escorted. The OS series continued until September, 1942 (OS.42) when it was suspended for five months to free resources for Operation Torch, the invasion of North Africa which began on November 8, 1942. The series recommenced in February 1943 and in April 1943 it was combined with the KMS series bound for Gibraltar, the two convoys separating en route. The OS series continued until May, 1945 (OS.131/KMS.105).

See also the entry for OS convoys and the KMS series in the Arnold Hague database.

For each convoy I have compared the data, which is derived from original sources contained in the National Archives, with that of Hague (Arnold Hague,'The Allied Convoy System 1939-1945', ISBN 1-55125-033-0). It should be noted, however, that in a number of early convoys Hague occasionally underestimates the total number of vessels - sometimes by as much as 50% (q.v.OS.14). Also, while Hague was quite accurate in giving the total numbers in the combined OS/KMS convoys, his apportion to the individual elements are often in error. Nevertheless, Hague's contribution is of enormous value and continues to provide us with information that would be difficult or impossible to obtain elsewhere.

When available, I have included the pendant number (position in convoy), home port, destination, cargo, nationality and armament for each vessel in convoy. Note, however, that prior to OS.49, Oban did not report the armaments carried on vessels so that a blank does not indicate an unarmed vessel. Also, I have added links (to self-closing panels) giving further information on the vessels lost both within and detached from convoy. Vessels that had intended to travel in convoy but did not sail are noted in the database since this information is also valuable when researching individual vessel movements. Often, vessels that did not sail can be found in the preceding or subsequent convoy. Wherever possible, the original port lists have been cross-checked with the cruising order chart to maintain accuracy, resolving name differences by reference to 'Der Handelsflotten der Welt 1942', ISBN 3-469-00552-4.

There is surprisingly little data available on the Internet concerning the composition of individual convoys. Data on some HX, ON, ONS and SC series (mainly North America - UK) may be found on the warsailors web site which is being continually updated.

The author wishes to express thanks to Dominique Lemaire for diligently proofreading these convoy pages.