Editing Convoy (section)

===World War I===
{{main|Convoys in World War I}}
In the early 20th century, the [[HMS Dreadnought (1906)|dreadnought]] changed the balance of power in convoy battles. Steaming faster than merchant ships and firing at long ranges, a single [[battleship]] could destroy many ships in a convoy before the others could scatter over the horizon. To protect a convoy against a capital ship required providing it with an escort of another capital ship, at very high [[opportunity cost]] (i.e. potentially tying down multiple capital ships to defend different convoys against one opponent ship).

Battleships were the main reason that the [[British Admiralty]] did not adopt convoy tactics at the start of the [[Atlantic U-boat campaign of World War I|first Battle of the Atlantic]] in [[World War I]]. But the German capital ships had been bottled up in the North Sea, and the main threat to shipping came from [[U-boat]]s. From a tactical point of view, World War I–era [[submarine]]s were similar to privateers in the age of sail. These submarines were only a little faster than the merchant ships they were attacking, and capable of sinking only a small number of vessels in a convoy because of their limited supply of torpedoes and shells. The Admiralty took a long time to respond to this change in the tactical position, and in April 1917 convoys were trialled, before being officially introduced in the Atlantic in September 1917.
[[File:British Convoys during the First World War Q19954.jpg|thumb|British convoy in the Atlantic during World War I]]
Other arguments against convoys were raised. The primary issue was the loss of productivity, as merchant shipping in convoy has to travel at the speed of the slowest vessel in the convoy and spent a considerable amount of time in ports waiting for the next convoy to depart. Further, large convoys were thought to overload port resources.

Actual analysis of shipping losses in World War I disproved all these arguments, at least so far as they applied to transatlantic and other long-distance traffic. Ships sailing in convoys were far less likely to be sunk, even when not provided with an escort. The loss of productivity due to convoy delays was small compared with the loss of productivity due to ships being sunk. Ports could deal more easily with convoys because they tended to arrive on schedule and so loading and unloading could be planned.

In his book ''[[On the Psychology of Military Incompetence]]'', Norman Dixon suggested that the hostility towards convoys in the naval establishment were in part caused by a (sub-conscious) perception of convoys as effeminating, due to warships having to care for civilian merchant ships.<ref>Dixon, Dr. Norman F. ''On the Psychology of Military Incompetence'' Jonathan Cape Ltd 1976 / Pimlico 1994 pp. 210–211</ref> Convoy duty also exposes the escorting warships to the sometimes hazardous conditions of the North Atlantic, with only rare occurrences of visible achievement (i.e. fending off a submarine assault).