Gibraltar convoy routes crossed U-boat transit routes from French Atlantic ports and were within range of Axis maritime patrol aircraft making these convoys vulnerable to observation and interception by bombers, submarines, and surface warships during the Battle of the Atlantic.

The Battle of the Atlantic was fought around merchant ships carrying supplies to and from the British Isles.

Proximity to Francoist Spain and Fascist Italy made this traditional trade route vulnerable to hostile observation and interception.

Protection of this shipping route was similarly important to France for trade with colonial North Africa, Syria, Lebanon, Madagascar, and Indochina.

[1] Most shipping to and from the Indian Ocean and the eastern Mediterranean was diverted around Africa until the surrender of Italy.

OG and KM convoys consisted largely of supplies for the military garrisons and civilian populations of Gibraltar and Malta, and for Operations Torch and Husky.

Early convoys were escorted by French warships to the vicinity of Ushant where ships bound for east coast ports detached to proceed through the English Channel until the surrender of France in June 1940.

[5] 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.

[6] Slow convoys returning from the Mediterranean to the United Kingdom after Operation Torch were designated MKS replacing the former HG series.

Convoy KMS 1 was part of Operation Torch leaving the Firth of Clyde on 22 October 1942 to reach Algiers on 8 November.

As the Mediterranean became more secure, KMF convoys included troopships carrying soldiers to the Indian Ocean.

[9] Fast ships returning from the Mediterranean to the United Kingdom formed MKF convoys.