Encyclopedia - The Dover Barrage

Sir Roger Keyes, Chairman of the Barrage Committee The Dover Barrage comprised an (ultimately successful) attempt by the British Navy to prevent the access of German U-boats through the English Channel at the latter's narrowest point.

The preparation of the Dover Barrage in earnest was preceded in the war's first month by the laying of a vast minefield between the coast of Belgium and Dover, similarly designed to prevent enemy U-boat access.

Begun in February 1915 the Dover Barrage consisted of a 25km series of so-called light steel indicator nets anchored to the sea bed at various depths and used to effectively capture enemy submarines by entanglement.  The indicator nets were accompanied by minefield layers, also at various depths.  Finally, British destroyers were deployed to patrol the area.

Once the barrage was laid the initial signs were good with an early success secured by the British on 4 March 1915, the German U-boat U-8 claimed victim, caught in the indicator nets.  Shocked, the German Navy was forbidden to use the English Channel for what eventually amounted to a year pending reconsideration of tactics.

Fortunately for the British there was a mutual tendency on both sides to account for unexplained submarine losses - often incorrectly - to the Dover Barrage.

Yet the barrage was by no means impassable, not least on account of the unreliability of then-available British mines.  Further, the indicator nets had been unevenly laid, leaving gaps through which submarines could weave.  Nor was the area patrolled as often as was necessary owing to a shortage of available destroyers. 

The self-imposed German exile from the English Channel was ended in March 1916 when U-boats were despatched from the German-controlled ports of Zeebrugge and Ostend.  The Germans found that they could readily pass through the barrage, with many even coasting along the surface of the Channel under cover of darkness.

Once again the British worked to improve effectiveness of the barrage, spending two months from November 1917 shifting it east between Folkestone and Cap Gris Nez.  Sir Roger Keyes was placed at the head of the Barrage Committee to monitor its operational success and liaise with Dover Patrol commander Sir Reginald Bacon.

With the adoption of far more effective H-2 mines and night patrols with searchlights, plus an ongoing increase in minefield coverage, efficiency of the Dover Barrage was improved, claiming a further dozen U-boat victims until the German Navy ceased attempting the Channel from the middle of August 1918.

The belated success of the Dover Barrage led in 1918 to deployment of the markedly less triumphant Northern Barrage in the North Sea.  Nor was the Otranto Barrage, constructed during the autumn of 1915, any more successful.

A "blimp" was a word applied to an observation balloon.

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