She was 75 feet below the surface when a loud explosion was heard. The torpedo had got home. The noise was so great that the commander thought the shell of his boat had been damaged by the collision, and that it was collapsing under the pressure of the water. He therefore rose to 60 feet, but the sound of the approaching screw of a large ship forced him to dive to 80 feet. Again and again he tried to rise, but every time he heard the screws of battleships and torpedo boats above him. He now discovered that his periscope was damaged, and that his boat was leaking and losing its buoyancy. Water had to be blown out of the tanks from time to time, and this revealed the presence of the submarine to the ships above. It was not until near midnight that she dared come to the surface. She rose carefully, and, thanks to the darkness, was not seen. Soon she was making her way to the shore, having been under water for four hours without a break. * * * * * About the second week of May German submarines were reported in the Mediterranean. During the month of February the Germans completed the first of their big submarines which were capable of making the journey from Zeebrugge to the Dardanelles within three weeks. Secret bases had been established in Eastern waters, and the British Government offered a large reward for their discovery. Several of them were found on Greek islands. Before long the German submarines made their presence felt. We shall learn in a later chapter how, on 26th May, one of them managed to torpedo the _Triumph_, and the next day sent the _Majestic_ to the bottom. The submarines practically put an end to the bombardment of the Dardanelles forts by our ships of war. While firing at the forts the ships were obliged to move slowly, and thus were at the mercy of an enemy under water. Germany's new submarines in the Mediterranean mounted bigger and more effective guns than had formerly been employed on under-water craft, and they were able to destroy several vessels by shell fire. Not only British, French, and Italian vessels were sent to the bottom, but one if not two American ships. I have already told you of the sinking of the _Ancona_. Dastardly as it was, it was outdone on 30th December, when the Peninsular and Oriental liner _Persia_ was sent to her doom. She was on her outward voyage, and at lunch time was off the island of Crete, when, without warning of any kind, a torpedo was launched against her. Five minutes after she received her death-blow she had vanished utterly. More than 330 out of the 501 passengers and crew were lost, and amongst the victims were a large number of women and children. Lord Montagu, who was saved, cabled home as follows:--