The mines were deployed from underwater.  Each mine dropped to the seabed from a chute.  A dis-solvable plug which reacted with seawater allowed the sub to move away a safe distance before it released a mechanism to allow the mine to float clear of its anchor weight and it rose to a pre-set distance on a cable. The distance was calculated to be always underwater, so invisible, but high enough to strike a ships hull.

An egg mine sketch with the release mechanism

To counter the threat ordinary fishing boats and fishermen were recruited under the Royal Navy Minesweeping Reserve. With some basic training they were redeployed to various ports and waterways.  Many were steel built steam drifters of 2-300 tons and up to 140 foot long.  The skipper and crew were not under naval discipline or expected to wear a uniform.  Their orders came from the Navy.

The method used initially was crude and risky. Two ships with a sunken cable strung between them scoured the channels in order to keep them clear for shipping. The risk was that ships needed to maintain a steady drag as any deviation might allow a snared mine to travel along the cable and strike one of the towing vessels.  By 1916 the method was improved with a kite system which allowed the cable to be steadier, and to ensure that any travelling mines exploded some distance from the ships. Serrated cables were also introduced, but these tended to be only effective with more powerful ships.

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There was two techniques for dealing with mines.  They could be towed and if their anchoring cables snapped the mine which floated to the surface could be destroyed by gun fire.  Alternatively the snared mine could be towed into shallow water where it floated onto the surface and could then be dealt with.  Unfortunately steam trawlers for fishing were not built with military purposes in mind, and so unlike naval purpose built vessels with double hulls, they were more susceptible to underwater explosions.

City of York, a typical steam trawler of the time

During WWI 726 vessels were employed in mine sweeping and over 250 of them were lost, 214 to mines.  I have not yet come across any details of their operations in Dunmore or the harbour.  But we saw previously how its speculated they may have played a role in luring UC-44 to her doom in Dunmore East.  Two Mine Sweepers that we know of were lost off Dunmore.

The first was HMT Loch Eye, a steam trawler built by the Torry shipbuilders of Aberdeen.  She was built for a local company, the Empire Steam Fishing Company Ltd.  She was requisitioned by the Royal Navy for mine sweeping duties in September 1916.  On April 20th 1917 while operating off Dunmore East she struck a mine and sank with the loss of seven lives.

These were:

The mine had been laid by UC-33 which was rammed and sank in the following September.  All but one crew of the 28 aboard were killed.

In July another mine-sweeping vessel was lost, the HMT George Milburn.   From what I have read it appears she was on escort duty, en route from Cobh to Milford Haven.  She struck a mine off Dunmore on Thursday July 12th and sank with the loss of 11 lives.

The mine she struck had been laid by UC-42, which was lost in Cork Harbour in September, with the death of all her crew.

The crews of both trawlers and UC-42 remembered in Templetown graveyard, Co Wexford photo via Michael Farrell BGHS

The events around Dunmore East in 1917 will be remembered this weekend when The Barony of Gaultier Historical Society (BGHS) under the chairmanship of Michael Farrell will host an event entitled Friend and Foe.  It sets out to shine a light on these events and bring, if you will pardon an obvious pun, more information to the surface.  It starts this evening with a walk at 4pm looking at the life and times of Dunmore harbour 100 years ago.  A full list of events are available on the BGHS blog page.

Much of the information used today was drawn from Jim Crossley’s book The Hidden Threat, The Royal Naval Minesweeping Reserve in WWI . 2011 Pen & Sword Maritme. Barnsley.  Thanks to Frank Murphy for providing me with the book

My Facebook and Twitter pages are more contemporary and reflect not just heritage

and history but the daily happenings in our beautiful harbour:

F https://www.facebook.com/whtidesntales  T https://twitter.com/tidesntales