The outlook at the end of 1915 was far from bright, and the minesweeping service was barely able to meet the strain in spite of the better design and greater number of its ships.
By the beginning of 1916 the hired paddle-sweeper force had grown to five units, numbering 35 vessels in all, and 14 sloops were in commission with the Grand Fleet. Twenty-four Admiralty paddlers of 810 tons and 634 ft. draught were being built and were distributed during the year between the Forth and Dover straits. A new type of twin-screw sweeper of 750 tons with a draught of only 7 ft., called the "Hunt" class, was completing and the whole batch of 12 was allocated to the Grand Fleet. The Burney paravane was also past its trial stage and by the end of the year was supplied to all ships of over 12 ft. draught. This instrument was the product of Lt. Denis Burney's genius. Shaped like a torpedo and about 12 ft. long, it was towed from a special shoe on each side of the bows, being held at its proper depth by a hydrostatic arrangement and at its proper distance by rudders. The mooring-wire of any mine it met was swept clear of the ship into jaws of serrated steel and quickly cut. The mine came to the surface and could be sunk. The "otter" was a modified form of paravane for use in merchant ships where its fitting became compulsory in 1917. The paravane justified its adoption: 180 warships and 2,740 merchant ships were fitted with it; in the former it cut 55 mine wires during the war, and in the latter at least 40 or 50. Another simpler but useful invention, in the form of a special sort of serrated wire for sweeping, also dates from 1916; it could cut through a mine's mooring-rope when towing it no faster than a trawler (4 to 5 knots) .
Surface minelayers were still active, and the raider "Moewe" on her way out to the ocean laid a large minefield of some 250 mines on New Year's day, 1916, on the west side of the Orkneys. Commencing about 10 m. from the Orkneys it ran in zig-zags at 3 to 7 m. from the mainland. The loss of the pre-dreadnought battleship " King Edward VII." on the morning of Jan. 5 was the first sign of it, and two neutral steamers were sunk in the same field. Gales interfered seriously with its clearance but by May some 71 mines had been destroyed. All other German mines laid in 1916 were laid by the submarine flotillas, which were now reinforced by a number of UC boats carrying 18 mines .and by several larger boats (U7i-8o) carrying 34 to 36. Some were attached to the Flanders Flotilla and worked from Bruges and Zeebrugge; others, including the larger minelayers, were attached to the High Sea Fleet and worked from the Elbe. Each of the two flotillas was allotted a separate area of the British coast for minelaying. The High Sea Fleet boats worked N. of Flamborough Head. The Flanders Flotilla area comprised the coastline from Flamborough Head to Dover, the English Channel, the Irish Sea and Irish S. coast to Waterford.
A field laid on the west coast of the Orkneys was to have an unforeseen result. It was laid on May 29 by the U75, one of the large minelayers, as part of the Jutland operations, and at 8 P.M. on June 6 the "Hampshire" on her way to Archangel struck a mine in it off Marwick Head, foundering almost immediately and bringing Lord Kitchener's career to a dramatic close. A trawler unit, searching the spot as soon as the weather moderated, found 15 mines laid at 7 metres in a spot where the strong cur- rent and tidal dip would have enabled the "Hampshire" to pass over them in a normal sea. From May to Oct. 1916 German minelaying in the English Channel ceased as a result of an imperial order, dictated by the American note of April 18, to con- fine submarine warfare strictly to the conditions of prize law. Scheer went further than the imperial command, and ordered his flotillas on April 24 to cease all operations against merchant ships, while the Flanders boats, following suit, limited them- selves to minelaying off Lowestoft, Harwich and the Nore.
In Oct. 1916 submarine operations against merchant shipping were resumed, and minelaying broke out with renewed activity. Mines were laid off the Clyde (Oct. 3) and in November off the Isle of Man. The close of 1916 saw a determined attack by the Flanders submarines against the ports in the Channel and mines were laid off Portsmouth, Dartmouth, Plymouth and Falmouth. The French coast opposite Dover was also heavily mined. In the Dover area 212 mines were laid during the year (not including too off Dunkirk, 100 off Calais and 60 off Boulogne), with a loss of two destroyers, five minesweeping trawlers and 20 steamers.
The unrestricted submarine warfare in 1917 was accompanied by an increase in submarine minelaying, and in the month of April 515 mines were swept up, considerably more than in any previous quarter. The reorganization of the naval staff led to considerable changes in the minesweeping service. The director of torpedoes and mining now took charge of the development, supply and distribution of gear, while the control of operations and the distribution of all vessels was delegated to a captain of minesweeping (Capt. Lionel Preston), who in Oct. 1917 became director of the minesweeping division under the assistant chief of the naval staff. Losses in minesweeping vessels were heavy in the early part of the year, amounting to as many as one per diem in April 1917, but the use of aircraft patrols and of shallow- draught motor-launches proved useful in locating mines and diminished the loss of heavy-draught sweepers. The extended range of enemy minelaying and the heavy losses amongst mine- sweepers led to an increased demand for them. Thirty small paddle-steamers, 10 small tugs and 18 drifters were requisitioned, and orders were issued for the construction of 100 more "Hunt" class (800 tons, 7ift. draught, 18 knots) and 300 drifters.
The war channel now ran up the east coast as far as the Tees in the shoalest possible water, and shipping was released from various night anchorages in the Downs, Black Deep and Great Yarmouth as soon as it had been swept at dawn. Improvements in organization during the year led to a reduction of 20% in merchant-ship losses, though the mines swept up were double those in 1916.
The operations of the High Sea Fleet Flotilla were extended in the spring of 1917 to the Minch and the routes of the west coast of Scotland used by destroyers and fleet auxiliaries, much of the work being done by the U8o, one of the large submarine minelayers. In 1916 195 distinct mine groups had been laid, chiefly on the east coast; in 1917 the number rose to 536 and the sphere of operations extended right round the British Isles. This involved a further expansion of the minesweeping service, and the fast sweepers (sloops, gunboats, paddlers) increased from 93 to 122, the slow (trawlers, drifters) from 430 to 509. The deep water off the Yorkshire coast had been a favourite cruising ground for submarines, but large protective minefields were now laid there as an off-shore protection with good results.
The Harwich area was exceptionally busy in 1917, and its work in that year must rank as one of the principal minesweeping achievements of the war. Mines were regularly laid by German submarines in the latter part of the year to catch the Holland trade, and a new minefield off the Maas Light, laid in April 1917 and regularly renewed, became a source of constant trouble. Out of 680 mines laid 633 were destroyed, with the loss of four merchant ships and eight minesweepers. The enemy had to pay a heavy toll for his work, and lost 12 minelaying submarines in the southern portion of the North Sea during 1917. The port of Liverpool, as the principal arrival base for Atlantic transports, was a constant source of anxiety, and at the beginning of 1917 had only two minesweeping trawlers attached to it. Mines were reported there on March 24 1917, and on April 9 the "New York," with Adml. Sims on board, struck a mine, but the port was fortunately left alone till December, by which time the protective arrangements had greatly improved. Of 45 mines laid in the Mersey area 33 were accounted for, with the loss of five mer- chant ships and one pilot steamer in which 28 pilots lost their lives. In the W., Lough S willy and the approaches to the Clyde were all mined during 1917, some 88 mines being laid in this area and off Belfast, of which 72 were destroyed, with the loss of four steamers, one destroyer and five trawler minesweepers. The south coast of Ireland also became a regular region of visitation, and the small tidal range and heavy swell made minesweeping particularly dangerous there. The loth Sloop Flotilla was sent from Immingham to Queenstown in Feb. 1917 to cope with the new danger, and two of its sloops were mined in the following
