Convoy

Convoy, assembly of supply ships or vehicles accompanied by an armed escort for protection. Mercantile convoys were common in the Middle Ages, when traders travelled in large caravans or in large fleets for mutual protection against pirates. In modern times, columns of vehicles guarded by military forces are called convoys. The term is most often applied to a naval convoy, escorted by warships, for the transport of troops and supplies overseas.

The modern naval convoy system is an outgrowth of the unrestricted submarine warfare begun by Germany early in 1917, during World War I. Before this time the Allies had found the system of patrolling sea-lanes adequate to protect lines of supply; but with increased action by German submarines, called U-boats, shipping losses became so great that the Allies were forced to adopt the convoy system. The average convoy consists of 12 to 40 supply ships or troop transports, protected by an escort of destroyers or other warships. The convoy system proved so successful that fewer than 500 ships of nearly 100,000 in total convoys were lost by the Allies.

German submarine warfare necessitated re-establishment of the convoy system by the Allies early in World War II. The system corresponded in general to that developed in World War I, except that aircraft were extensively used both to defend and attack convoys. Auxiliary aircraft carriers with scouting and attack aircraft were attached to major convoys, each of which often included more than 100 ships. Land-based aircraft provided cover within range of friendly bases, and fighter planes, catapulted from ships, furnished considerable protection against land-based enemy bombers. Aircraft were also effectively employed against convoys both alone and in conjunction with naval units.