"Admiral Lord Beresford's prescience eventually led to the formation of the Royal Naval Reserve (Trawler Section) - the RNR(T). The Trawler Reserve was instituted with approval for 100 trawlers to be mobilised during any period of strained relations and for the immediate enrolment of 1,000 officers and ratings to man these vessels. This brought a new rank, that of 'Skipper' RNR, into the Navy List and the first officer (Peter Yorston) enrolled at Aberdeen on 3 February 1911. By the end of 1911, 53 skippers had joined. In 1912 a further 25 enrolled and the Trawler Section of the Royal Naval Reserve consisted of 142 trawlers manned by 1,279 personnel. 31 more skippers joined before the war started in August 1914 making a total of 109. 315 more volunteered by the end of the first week in October. By the end of 1915 the Minesweeping Service employed 7,888 officers and men.

Within the first week of war, 94 trawlers were allocated for minesweeping duties and dispersed to priority areas including Cromarty, the Firth of Forth, the Tyne. the Humber, Harwich, Sheerness, Dover, Portsmouth, Portland and Plymouth. The groups were commanded by naval officers, some from the retired list, who had received a brief training in minesweeping. Apart from the skippers, officers were also required to supplement the handful of naval officers of the existing minesweeping service. Most of the trained pre-war RNR and RNVR officers had already been called up for service in the Fleet. For the new minesweeping and auxiliary patrol flotillas, officers and civilians were obtained from the Merchant Navy and given temporary commissions in the RNR and RNVR. To bolster naval discipline, various Royal Fleet Reserve and pensioner petty officers were distributed among the vessels.

When the Armistice was signed at the end of WW I, the Trawler Reserve consisted of 39,000 officers and men of whom 10,000 were employed in minesweepers and the rest in the auxiliary patrol. The 10 ex-torpedo gunboats available as minesweepers at the outbreak of the war had been replaced by purpose-built ships including 72 Flower Class single-screw fleet minesweeping sloops of the Acacia, Arabis and Azalea types, 107 Hunt Class and Improved Hunt (Aberdare) Class twin-screwed minesweepers, 24 'Class of 24' fleet sweeping sloops, 32 Ascot Class and Improved Ascot Class minesweeping paddle-steamers, 13 Grimsby Class general purpose sloops and 10 Dance Class 'Tunnel Tug' inshore minesweepers. Total RN minesweeping forces included 762 ships stationed at 26 home ports and 35 foreign bases. 214 minesweepers had been lost during the four years and three months of the war."

https://www.mcdoa.org.uk/RN_Minewarfare_Branch.htm