On July 25th, 1915, the _Prince Charles_ (Lieutenant W. P. Mark-Wardlaw--of Admiral Colville’s staff--in command) sighted, near North Rona Island, the Danish steamer _Louise_, stopped and with a submarine close to. When the submarine sighted the _Prince Charles_ she proceeded at full speed towards her and opened fire at 5,000 yards’ range. Lieutenant Mark-Wardlaw stopped his engines and went through the usual process of lowering boats in a great hurry. The submarine, which was the U 36, closed to within 500 yards, still on the surface, and at that range the _Prince Charles_ revealed her true character, unmasked her guns, and opened a most accurate fire with her two 6-pounders and two 3-pounders. The U 36 was immediately holed, and two men killed in the conning tower. She was unable to dive and sank stern first; 4 commissioned officers, 2 warrant officers, and 9 men were saved by the _Prince Charles_. CHAPTER X ATTEMPTS TO ENTICE THE ENEMY TO ACTION The year 1916 opened and still no general action had been fought in the North Sea, which the Grand Fleet continued to dominate, paying its price--though not so heavy as might have been expected--for the influence it exerted on all the operations--naval, military and economic--to which the country had by that time been committed in face of the active operations pursued by enemy submarines and mine-laying craft. On January 5th the Battle Cruiser Fleet left Rosyth to cruise in the northern part of the North Sea, and returned during the night of the 8th–9th. The facility with which enemy mines could be laid in the vicinity of naval bases during the long winter nights, when there was little or no moon (as shown, _inter alia_, by our own mine-laying in the Heligoland Bight, which, though not very frequent in 1916, became constant in 1917), led me to extend still further the patrols from the bases at such times; from January 2nd to January 10th inclusive, the patrol vessels (two light cruisers and a destroyer) worked in an area about 140 miles and between bearings 80 and 130 degrees from the Pentland Firth, the ships being in the area by 2 P.M. each day. Similar patrols were ordered to be instituted from the Rosyth base. The enemy, however, instead of mining the exit from the bases to the eastward, selected the western approach to the Pentland Firth for the purpose, possibly because of the considerable mercantile traffic using this route. The patrols in this direction did not extend so far from the base, the sea being very frequently too heavy in the winter months; the practice was to search the route periodically for mines.