Air-raids were, however, one of the horrors of war rather than a means of achieving victory, and the military importance of aircraft never attained proportions corresponding to the space the subject occupied in the public press and the popular mind. They did not affect the duration of the war by a single day, and throughout the winter of 1915-16 it seemed to increase in horror without any other sort of progression on land or water. There was no naval action because Germany kept her fleet in harbour, and relied upon mines and submarines to wear down not so much the naval strength as the economic resources of the Allies. Occasionally a cruiser or smaller vessel was lost, and one pre-Dreadnought battleship, the Edward VII. But German successes were mostly scored against merchant vessels and similar craft; and our activities in the Balkans, coupled with the facilities afforded by the Aegean to submarines, made the Eastern Mediterranean a favourite scene for their operations. By the end of 1915 over a thousand vessels, Allied and neutral, of one sort or another, had been put out of action by mines and submarines; but the fact that few of them had any fighting value concealed the importance of their economic loss from the eyes of the public if not of the Government itself. A more legitimate and romantic form of depredation was the cruise of the Moewe, a disguised auxiliary cruiser, which succeeded in January and February 1916 in capturing fifteen British merchantmen in the Atlantic, and returned safe to Kiel with prisoners and booty. The absence of German commerce made British retaliation impossible except in the Baltic, where our submarines had some remarkable successes until Sweden closed the entrance by mining her territorial waters. She was within her rights in doing so, but the effect of her action was to give German commerce in the Baltic a security which was lacking to the commerce of the world outside, because Holland and Denmark shrank from following Sweden's example. Mr. Balfour pointed out the unfriendly nature of Sweden's action, but Russia was particularly averse from adding Sweden to her enemies at that juncture, and remonstrances were in vain.