The sinking of ships in the "war zone" continued in spite of rumors that the German admiralty was expected to discontinue operations of the submarines against merchantmen on account of the unfriendly feeling aroused in neutral nations, particularly the United States. On the 19th of May, 1915, came the news that the British steamship Dumcree had been torpedoed off a point in the English Channel. A torpedo fired into her hull failed to sink her immediately, and a Norwegian ship came to her aid, passing her a cable and attempting to tow her to port. But the submarine returned, and fearing attack, the Norwegian ship made off. A second torpedo fired at the Dumcree had better effect than the first one, and she began to settle. When the submarine left the scene the Norwegian steamship again returned to the Dumcree and managed to take off all of her crew and passengers. Three trawlers, one of them French, were sunk in the same neighborhood during the next forty-eight hours.
As soon as Italy entered the war an attempt was made by the Teutonic Powers to establish the same sort of submarine blockade in the Adriatic which obtained in the waters around Great Britain. This was evinced when the captain of the Italian steamship Marsala reported on May 21, 1915, that his ship had been stopped by an Austrian submarine, but the latter not wishing to disclose its location to the Italian navy, allowed his ship to proceed unharmed.
The suspicion that the German admiralty maintained bases for their submarines right on the coasts of Great Britain where the submersible craft could obtain oil for driving their engines, as well as supplies of compressed air and of food for the crew, was confirmed on the 14th of May, 1915, when it was reported that agents of the British admiralty had discovered caches of the kind at various points in the Orkney Islands, in the Bay of Biscay, and on the north and west coasts of Ireland.
In order to damage shipping in the "war zone" by having ships go wrong through having no guiding lights an attack was made by a German submarine on the lighthouse at Fastnet, on the southern coast of Ireland, on the night of May 25, 1915. Shortly after nine in the evening the submarine was sighted in the waters near the lighthouse by persons on shore. She was about ten miles from Fastnet, near Barley Cove. When she came near enough to the lighthouse to use her deck guns, men on shore opened fire on her with rifles, and she submerged, not to reappear in that neighborhood again.
But this same submarine managed to do other damage. The American steamship Nebraskan was in the neighborhood on its way to New York. The sea was calm and the ship was traveling at 12 knots, when some time near nine o'clock in the evening a shock was felt aboard. A second later there came a terrific explosion, and a subsequent investigation showed that a large hole, 20 feet square, had been torn in her starboard bow, not far from the water line. When she began to settle the captain ordered all hands into the small boats. They stayed near the damaged ship for an hour and saw that she was not going to sink. When they got aboard again they found that a bulkhead was keeping out the water sufficiently to allow her to proceed under her own steam. In crippled condition she made for port, being convoyed later by two British warships which answered her calls for help.
In spite of the sharp diplomatic representations which were at the time passing back and forth between Germany and the United States over the matter of the German submarine warfare, the craft kept up as active a campaign against merchant ships as they did before the issues became pointed. On May 28, 1915, there came the news that three more ships had been sent to the bottom. The Spennymoor, a new ship, was chased and torpedoed off Start Point, near the Orkney Islands. Some of her crew were drowned when the lifeboat in which they were getting away capsized, carrying them down. On the same day the large liner Argyllshire was chased and fired upon by the deck guns of a hostile submarine, but she managed to get away. Not so fortunate, however, was the steamship Cadesby. While off the Scilly Islands on the afternoon of May 28, 1915, a German submarine hailed her, firing a shot from a deck gun across her bows as a signal to halt. Time was given for the crew and passengers to get into small boats, and when these were at a distance from the ship the deck guns of the submarine were again brought into action, and after firing thirty shots into her hull they sank her. The third victim was the Swedish ship Roosvall. She was stopped and boarded off Malmoe by the crew of a German submarine. After examining her papers they permitted her to proceed, but later sent a torpedo into her, sinking her.
A new raider, the U-24, made its appearance in the English Channel during the last week in May, 1915. On the twenty-eighth of the month this submarine sank the liner Ethiope. The captain of the steamship attempted some clever maneuvering, which did not accomplish its object. He paid no attention to a shot from the deck guns of the submarine which passed across his bow. The hostile craft then began to circle around the liner, while the rudder of the latter was put at a wide angle in an effort to keep either stern or bow of the ship toward the submarine, thus making a poor target for a torpedo. But the commander of the submarine saw through the movement and ordered fire with his deck guns. After shells had taken away the ship's bridge and had punctured her hull near the stern the crew and passengers were ordered into the small boats. They had hardly gotten twenty feet from their ship when she was rent by a violent explosion and went down.
The transatlantic liner Megantic had better luck, for she managed to escape a pursuing submarine on May 29, 1915, as she was nearing Queenstown, Ireland, homeward bound. A notable change in the methods adopted by the commanders of submarines as a result of orders issued by the German admiralty in answer to the protests throughout the press of the neutral nations after the sinking of the Lusitania was the giving of warning to intended victims. By the end of May, 1915, in almost every instance where a German submarine stopped and sank a merchantman the crew was given time to get off their ship and the submarine did not hesitate to show itself. In fact, warning to stop was generally given when the submarine's deck was above water and the gun mounted there had the victim "covered." This was done in the case of the British steamship Tullochmoor, which was torpedoed off Ushant near the most westerly islands of Brittany, France.
On the 1st of June, 1915, there came the news of the sinking of the British ship Dixiana, near Ushant, by a German submarine which approached by aid of a clever disguise. The crew managed to get off the ship in time; when they landed on shore they reported that the submarine had been seen and on account of sails which she carried was thought to be an innocent fishing boat. The disguise was penetrated too late for the Dixiana to make its escape.
The clear and calm weather which came with June, 1915, made greater activity on the part of German submarines possible. On the 4th of June, 1915, it was reported by the British admiralty that six more ships had been made victims, three of them being those of neutral countries. In the next twenty-four hours the number was increased by eleven, and eight more were added by the 9th of June, 1915.