The U-Boat war develops

British E-Class Submarine

The invention and development of submarines led to step change in war at sea, as did the development of air power in later conflicts.  The first submarines, or 'submersibles', dated back to the 17th century, but it was in the American Civil War when an enemy vessel was first sunk by one, and the late 19th century when gains in mechanical power increased their scope. They threatened the end of conventional engagements between single warships and fleets, with the striking of colours to end engagements.  Traditionalists viewed submarines (U-Boats) with distaste, and felt they sank to new depths (sic) in the dishonourable conduct of naval warfare. Nevertheless, their potential was enormous.

When Churchill was appointed to the Admiralty in 1911, this scope and potential was barely appreciated. Although Britain had substantially more U-Boats than Germany, they were primitive and short range – thought to be of use only for the defence of home ports. In fact Germany had more of the sea-going quality vessels, and much more incentive for developing them. It was the British Empire’s vast merchant fleet that would be most vulnerable to hostile action from U-Boats. Overall, the Admiralty underestimated this threat - viewing it as both cowardly and inhuman, and therefore unlikely. Only Admiral Fisher (at that time First Sea Lord) differed. His memorandum of 1913 warned of precisely what would happen, but he was overruled. Partly, this was because there was not much that could be done about the German U-Boat threat. Britain building bigger and better U-Boats would not negate the German threat, and they would have no comparable targets to speak of (Nevertheless, they would prove their skills and worth during the Dardanelles campaign).

German UC-1 Class U-Boat

On 4^th February 1915 the German Admiralty declared all waters surrounding Great Britain and Ireland to be a war zone, and that all allied and neutral shipping would be subject to attack. Although disturbed by this, the British could see the potential political and propaganda advantages of this new situation. They, imbroiled as they were with the USA in lengthy arguments about the legality of their own North Sea block of trade with Germany, foresaw that tension would be removed if the Germans began to sink American or other neutral ships in the zone.  Home waters defences were strengthened by indicator nets at strategic points across narrow channels such as the Straits of Dover, and by Q Boats. These were essentially decoys, camouflaged as merchant or fishing vessels, but heavily armed. Other gadgetry rapidly appeared – hydrophones were trialled as an early version of sonar. In the first week of Germany’s offensive, 11 ships were attacked of which seven were sunk, but 1381 ships entered or left British ports safely. In the whole of March >6000 vessels arrived or sailed, of which only 21 were sunk. During the same period, German losses to the defensive strategies of the British were significant. By early May, this first attempt to strangulate British sea trade was effectively over – but it would return in a major way in 1917. Indeed, within weeks, on May 7^th in the Atlantic the Lusitania tragedy unfolded.