the outbreak of war in 1914 the British navy had, to some extent, realized the possibility of a mining offensive on the part of their enemies; and, largely due to the foresight of the late Admirals Lord Charles Beresford and Sir Doveton Sturdee, trawlers had been tested and had proved to be efficient minesweepers as early as 1907. A traw ler reserve purely for minesweeping was instituted shortly after wards. Thus, by August 8, 1914, 96 hired trawlers had put to sea to sweep up enemy mines, and within a fortnight another zoo trawlers had been requisitioned and were fitting out. The trawler minesweeper, however, did not entirely cover the requirements, as it was too slow to sweep the water ahead of a moving fleet; and this had been realised, and to some slight extent, catered for, by training a flotilla of eight old torpedo-gunboats. These ships were capable of towing the sweep at 12 knots, which was double the speed at which the majority of the trawlers could operate. This gunboat flotilla moved north from Dover on July 31, 1914, and, with sweeps out, actually covered the track over which the Grand Fleet passed. They were necessarily much overworked in the first six months of the war, as, whenever practicable, they swept the waters through which the fleet moved, and were also constantly required to search areas where mines were expected to be laid. The first batch of the special sweeping vessels, called sloops, was laid down in January 1915.
In British home waters the augmentation of the minesweeping force was less difficult than abroad. Light-draft excursion vessels (paddlers) were requisitioned in addition to the newly built craft already mentioned, and by April 1915, over 15o vessels were em ployed on minesweeping in home waters. In the Dardanelles 8 cross-channel steamers had augmented the trawler force, and a certain number of destroyers had been fitted for minesweeping.
By the beginning of 1916, 14 sloops had joined the Grand Fleet, and 35 hired paddlers were in action. The success of this latter type led to 24 being laid down by the Ad miralty, and also a new type of twin-screw sweeper, known as the "Hunt" class. The value of these ships lay in their sea-keeping qualities and shallow draught. The paravane (q.v.) also passed its test in 1916, and by the end of the year had been , supplied to 18o of H.M. ships. A modified form of this apparatus was fitted in merchant vessels; and, by the end of the war, 2,740 merchant ships had been fitted.
The intensity of minelaying and expansion of areas in the first half of 1917 was difficult to meet with the minesweepers avail able; and the climax was reached in April, with a loss of one minesweeper per diem for the greater part of that month. Prob ably no other service had a more severe strain placed on its per sonnel during this month and those immediately following. Every available and suitable paddle steamer and motor fishing boat had to be requisitioned; and those incapable of towing a heavy sweep were fitted with a light one, and used for search. Aircraft and motor launches were also used for low-water searches for mines, in order to reduce losses of sweepers; and improvements in traffic organisation and still closer co-operation between adjacent areas were gradually effected. Further protective minefields were laid in
certain suitable positions, but the opening of new areas was con stantly necessary; and, by the end of 1917, the coastal waters of Great Britain and Ireland, over c,000m. in extent, were being swept every day for mines. The war channel was also extended to the Firth of Forth, and merchant ships only released from a night shelter when they could proceed in freshly swept water. One hun dred new vessels of the "Hunt" class were laid down, and 30o new drifters put out to contract, so as gradually to replace and release trawlers for patrol and anti-submarine work.
The year closed with a total of 3,989 German moored mines swept up in home waters, at a cost of 17o Allied and neutral merchant ships sunk and 28 damaged. This total of mines for the year exceeded the combined totals for the previous years of the War. Nevertheless, the outlook was more hopeful. Although the intensity of minelaying had become so much greater, the losses had only been increased by nine ships over those of the previous year ; and progressive success in the destruction of submarines and their personnel made it evident that the same intensity and efficiency of the minelayers could not be continued much longer. New construction and greatly improved material for minesweeping had already made their mark. The only fear was that the mine sweep would be defeated by some innovation of the enemy. This fear, however, never materialised ; although a delayed action (whether intentional or otherwise) for releasing the mine from its sinker some hours after it was laid was observed on several occasions.
When the hour of the Armistice struck, a minesweeping force was waiting at the gate of the Dardanelles; and, within 24 hours, 600 British and enemy mines had been removed to clear the way for the fleet to Con stantinople. For one year after the War, mineclearing was con tinuous in every area where British or German mines had been laid. Under the difficult conditions which immediately followed the war, a special minesweeping force had to be enrolled. It con sisted of some 600 officers and 15,000 men. Over 23,000 Allied mines and some 7o German mines were Cleared from the sea by British minesweepers. No loss of a merchant ship by mine oc curred during that period ; and exactly one year to the day from the institution of this force the seas round Britain, her colonies and in the Mediterranean were reported clear. A fine perform ance in this respect was the clearing by the Americans of the mines laid between Orkney and the Norwegian coast. The Ger mans also commenced to clear the heavily mined areas in the Heligoland Bight, and later in the Baltic ; but this work of clear ance was not completed until 1923. Other nations concerned cleared their own coastal waters. (For military mines see FORTI