WORLD WAR I
HMS VERNON AND MINE WARFARE
1914-18
By Martin Kelly
University of Portsmouth HMS Vernon Postgraduate Research Group
If the Royal Navy had any doubts about the part the mine would play when war was declared on 4 August 1914, these were soon dispelled when the cruiser HMS Amphion was lost to mines laid by the German minelayer Königin Luise two days later.[1] It rapidly became clear that preparations made before the war for a trawler reserve to sweep mines were woefully inadequate and the sweeping operation developed quickly over the first years of the war. By April 1915, 237 vessels of various types were in use in the North Sea, by 1918 this had risen to over 3,000 vessels in all theatres.[2] 586 allied ships were lost to mines during the war compared with about 5,000 lost to U boats.
Mines used by Germany were moored contact mines[3] made by the Carbonit company; perversely, HMS Vernon had assessed these prior to the war for potential purchase by the Royal Navy thus they were well understood.[4] In the first two years of the war German mines were usually laid from a surface minelayer but from 1916 onward the preferred vehicle was submarines.[5] Towards the end of the war research was beginning in the Royal Navy and in the German navy on both the use of, and countermeasures against, influence mines: acoustic and magnetic[6], and some limited deployment of them was made by the RN off Zeebrugge.[7]
The main RN method of sweeping during the war was the A Sweep, employing a sweep wire towed by two vessels and kept at the required depth by the use of a kite. The French had developed a method of single ship sweeping using two wires deployed by kites kept at the required depth by a float and details are contained in a minute sent to the Grand Fleet in 1914. It was not until 1918, however, that the RN Oropesa Sweep (very similar to the French pattern) was brought into use.[8] It was named after the trawler Oropesa in which Commander Dennison, its inventor, served between 1916 and 1918. The limiting factor was that it only allowed sweeping at 6 Knots thus increasing the time taken to sweep a field compared with the A sweep.[9]
Apart from the North Sea, the Dardanelles Isthmus presented some of the most challenging minesweeping for the Royal Navy, owing to a combination of very strong tides and a continual bombardment from Turkish shore batteries.[10] It was the failure to guarantee the passage of the Dardanelles free from mines, and thus allow naval forces to pass through, that led to the decision to land troops at Gallipoli to disable the Turkish forts.[11] The disastrous outcomes of this decision need no further retelling.
The Royal Navy also made use of mines in an offensive capacity from 1915 onwards, particularly in the Heligoland Bight, and also the two barrages: across the Dover Strait and, towards the end of the war, the vast barrier from the Orkneys to Norway. By the end of the war, 131,000 mines had been laid by the Royal Navy and over 60,000 remained in stock.
Throughout the war, HMS Vernon was central to all of these activities, training trawler and destroyer crews in sweeping, developing sweeping techniques including fast sweeping and trials of cutters and serrated wires, as well as researching and training mine laying operations.[12]
[1] ADM 186/604 History of Mine Sweeping in the war Confidential Book 1553 1920 9.
[2] Ibid,
[3] Mines tethered by wire to a sinker, floating just below the surface and triggered by contact with a ship
[4] ADM 189/333 HMS Vernon Annual Report 1913
[5] ADM 186/604 8
[6] Mines lying on the sea bed actuated by the noise or magnetic signature of a passing ship. As these are not tethered by a wire, they cannot be swept by a sweep wire.
[7] E N Poland, the Torpedomen 80
[8] ADM 137/1886 Grand Fleet Orders/signals/correspondence p 452
[9] Ibid 555
[10] NRS The Keyes Papers Nos 66 and 69
[11] Christopher Bell, Churchill and Sea Power 69-70
[12] E N Poland, The Torpedomen 68-80
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