No. 85 The Menace beneath the Sea – the Minelaying Submarine (Diary of the War No.11)

New Developments in the War

This month sees the centenary of the sinking of two torpedo boats on 10 June 1915 as the war entered a new phase. Increased enemy activity around the entrance to the Thames between June 1 and June 9, 1915, was a cause of concern: one of the ships lost during this period was another interned German vessel now serving as a British collier, the Erna Boldt, on June 9 (see last month’s post on the Horst Martini).

The source of this activity required investigation and triggered a ‘vigorous submarine hunt by the Nore Defence Flotilla’, which included torpedo boats TB 10 (Greenfly) and TB 12 (Moth). (1) These two vessels belonged to the Cricket class of torpedo boat, their names redolent of their intended function as small, light, fast, darting attack vessels.

TB 12 was the first to sink, 2 miles NE of the Sunk Light Vessel, ‘when an explosion wrecked her fore-part and killed her commanding officer.’ TB 10 closed in to assist and take her in tow, when she herself succumbed to an explosion which broke her in two. The apparent track of a torpedo was seen heading towards her by a vessel in company, the Vulture, which set off in the direction of the torpedo’s trajectory.

It was later suggested, however, that the flotilla saw what they were expecting to see, namely a torpedo fired from a submarine: ‘they were, as on so many occasions, deceived.’ There was certainly U-boat activity in the area, but it was clear that the U-boat threat was no longer merely from attack submarines armed with torpedoes: there was a new, and worrying, threat. ‘Their loss represented the first fruits of the new German policy of laying minefields from specially built submarine-minelayers.’

Crew of a German UC-1 class submarine. Geiser Theodore (Mons) Collection. © IWM Q 20220
Crew of a German UC-1 class submarine. Geiser Theodore (Mons) Collection. © IWM Q 20220

UC 11 was the first of these new submarines to become operational, joining the Flanders Flotilla. She was nearly lost on her first mission to sow 12 mines in the Dover Barrage. Although she avoided the British defensive mines of the barrage, she fouled a buoy which she could not shake off, leading to a hunt by two successive British patrols, which she successfully managed to evade to fulfil her deadly mission.

On her next voyage, she also managed to break free of a British defensive net to deposit another deadly cargo of mines near the Sunk Light Vessel, which were those that accounted for the Erna BoldtTB 10 and TB 12. (2)

Had she succumbed to British defences on either mission, it is conceivable that this month I would be writing about the loss of the first operational UC-class submarine, rather than the first ships claimed by this new development in warfare: indeed, there were investigations into how UC-11 had literally slipped through the net not once, but twice. It was to be 1918 before UC-11 was sunk in her turn: reflecting her chief field of operations, less than a hundred miles from her Flanders base, she too now lies off the Sunk Light Vessel near her first victims.

(1) Naval Staff Monographs (Historical) Vol. XXIII, Home Waters – Part IV, from February to July 1915. Admiralty, London, 1925, pp253-5, from which all quotations are taken.

(4) ibid;

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