Second Kattegat raid

On 15 April 1918 British light warships attacked German vessels in the Kattegat, the strait between Denmark and Sweden, for the second time in half a year. The British chronology of the war records that day a “raid by British light naval forces into the Kattegat” and refers back to the previous raid of 2 November 1917. According to British chronicles of the war, Royal Navy ships sank ten German armed trawlers, and their crews were rescued. The available studies do not give the detailed course of the action, the composition of the British force or the names of the vessels sunk.

The U-boats’ route

In 1918 the Kattegat became one of the most important routes of the German submarines. The British were blocking the exits from the Heligoland Bight with ever denser minefields. According to Henry Newbolt’s British official history of the naval war, from February 1918 German submarines almost ceased to use them and went out into the Atlantic almost exclusively through the Baltic, the Danish straits and the Kattegat. The route was longer and cut every war patrol short by about four days, but it was safer. Admiral Reinhard Scheer recalled that this forced the German fleet to extend its minesweeping to the Kattegat and to counter the British mines laid from the Skaw towards the coast of Sweden. The minesweepers and armed trawlers that cleared the fairway and escorted the submarines, as well as the German fishing boats on the rich fishing grounds of the Kattegat, were therefore a constant target of British raids.

In its report for 1918 the British War Cabinet wrote that ships of the Grand Fleet frequently swept not only the North Sea, hunting for airships and German warships, but also the Kattegat, “for the purpose of sinking enemy minesweepers and fishing vessels”. The raid of 15 April was one such sortie. As in November 1917, the British operated right next to the neutral coasts of Denmark and Sweden, and the German vessels, lightly armed and slow, stood no chance against warships.

The raid did not, however, close the Kattegat. Newbolt admits that the British mine barrage laid in the strait was no obstacle to the German submarines, and that the Germans speeded up refits and shortened crews’ leave in order to keep the same number of boats on the approaches to British ports despite the longer route. The submarines continued to go out into the Atlantic through the Kattegat.