On the 20th of June, 1915, the day's reports of losses due to the operations of German submarines, issued by the British Government, contained the news of the sinking of the two British torpedo boats, the No. 10 and the No. 20. No details were made public concerning just how they went down.
On the same day the Italian admiralty announced that a cache maintained to supply submarines belonging to the Teutonic Powers and operating in the Mediterranean, had been discovered on a lonely part of the coast near Kalimno, an island off the southwest coast of Asia Minor. Ninety-six barrels of benzine and fifteen hundred barrels of other fuel were found and destroyed. It was believed that this supply had been shipped as kerosene from Saloniki to Piraeus. How submarines belonging to Germany had reached the southern theatre of naval warfare had been a matter of speculation for the outside world. But on the 6th of June, 1915, Captain Otto Hersing made public the manner in which he took the U-51 on a 3,000 mile trip from Wilhelmshaven on the North Sea to Constantinople. He was the commander who managed to torpedo the British battleships Triumph and Majestic.
He received his orders to sail on the 25th of April, 1915, and immediately began to stock his ship with extra amounts of fuel and provisions, allowing only his first officer and chief engineer to know the destination of their craft. He traveled on the surface of the water as soon as he had passed the guard of British warships near the German coast; traveling "light" allowed him to make six or seven knots more in speed. As he passed through the "war zone" he kept watch for merchantmen which might be made victims of his torpedo tubes. His craft was sighted by a British destroyer, however, off the English coast and he had to submerge to escape the fire of the destroyer's guns. He then proceeded cautiously down the coast of France, encountering no hostile ships. When within one hundred miles of Gibraltar he was again discovered by British destroyers, but again managed to escape by submerging his craft.
Passage through the Strait of Gibraltar was made in the early morning hours, while a mist hung near the surface of the water and permitted no one at the fort to see the wake of the U-51's periscope. Once inside the Mediterranean he headed for the south of Greece, escaping attack from a French destroyer and proceeding through the Ægean Sea to the Dardanelles. The journey ended on the 25th of May, just one month after leaving Wilhelmshaven.
The British ships Triumph and Majestic were sighted early in the morning, but attack upon them was difficult on account of the destroyers which circled about them; one of the destroyers passed right over the U-51 while she was submerged. Captain Hersing brought her to the surface soon afterward and let go the torpedo which sank the Triumph. For the next two days the submarine lay submerged, but came up on the following day and found itself right in the midst of the allied fleet. This time the Majestic was taken as the target for a torpedo and she went down. Again submerging his vessel Captain Hersing kept it down for another day, and when he again came to the surface he saw that the fleets had moved away. He then returned to Constantinople.
On the 23d of June, 1915, the British cruiser Roxborough, an older ship, was hit by a torpedo fired by a German submarine in the North Sea, but the damage inflicted was not enough to prevent her from making port under her own steam.
The deaths of a number of Americans occurred on the 28th of June, 1915, when the Leyland liner Armenian, carrying horses for the allied armies, was torpedoed by the U-38, twenty miles west by north of Trevose Head in Cornwall. According to the story of the captain of the vessel, the submarine fired two shots to signal him to stop. When he put on all speed in an attempt to get away from the raider her guns opened on his ship with shrapnel, badly riddling it. She had caught fire and was burning in three places before he signaled that he would surrender. Thirteen men had meanwhile been killed by the shrapnel. Some of the lifeboats had also been riddled by the firing from the submarine's deck guns, making it more difficult for the crew to leave the ship. The German commander gave him ample time to get his boats off.
To offset the advantage which the Germans had with their submarines the British admiralty commissioned ten such craft during the week of June 28, 1915. These vessels were of American build and design and were assembled in Canada. During the week mentioned they were manned by men sent for the purpose from England. Each was manned by four officers and eighteen men, to take them across the Atlantic. Never before in history had so many submarines undertaken a voyage as great. They got under way from Quebec on July 2, 1915, and proceeded in column two abreast, a big auxiliary cruiser, which acted as their escort steaming in the center.
The next large liner which had an encounter with the German submarine U-39 was the Anglo-Californian. She came into Queenstown on the morning of July 5, 1915, with nine dead sailors lying on the deck, nine wounded men in their bunks, and holes in her sides made by shot and shell. She had withstood attack from a German submarine for four hours. Her escape from destruction was accomplished through only the spirit of the captain and his crew, combined with the fact that patrol vessels came to her aid forcing the submarine to submerge.
A variety in the methods used by the commanders of German submarines was revealed in the stopping of the Norwegian ship Vega which was stopped on the 15th of July, while voyaging from Bergen to Newcastle. The submarine came alongside the steamship at night and the commander of the submarine supervised the jettisoning of her cargo of 200 tons of salmon, 800 cases of butter, and 4,000 cases of sardines, which was done at his command under threat of sinking his victim.