Mudros in itself offered nothing to the Allied fleets but a safe anchorage. It could not even supply the ships with fresh water, let alone meat, bread and vegetables. The island produces little for its few inhabitants; its wealth of a few goats, fish, olives and currants could be bought up in a week by the crew of one battleship. Everything necessary for the operations had therefore to be brought by sea and stored in Mudros till wanted. When this is grasped, the difficulties of the undertaking will be understood. There was no dock, wharf nor crane in Mudros, nor any place in the harbour where a dock or wharf could be built without an immense labour of dredging. Ships could not be repaired nor dry-docked there, nor could they discharge and receive heavy stores save by their own winches and derricks. Throughout the operations, ships had to serve as wharves, and ships' derricks as cranes, and goods were shipped, re-shipped and trans-shipped by that incessant manual labour which is the larger half of war. On the 18th February and following days, the Allied Fleets attacked the forts at the entrance to the Straits and soon silenced them. These were old-fashioned stone structures of great strength, they were knocked about and made untenable by the fire from the ships, but not destroyed. After this first easy success came delay, for the real obstacles lay within the Straits, between Cape Helles and the Narrows. Here, at intervals, very skilfully laid, commanded by many guns, ranged to the inch, were eight big mine fields, stretching almost across the navigable channel in different directions. No ships could pass this part of the Straits until the mines had been groped for and removed. In thick and violent weather, under heavy fire, and troubled by the strong current, the mine-sweepers began to remove them, helped by the guns of the fleet. But the fleet's fire could not destroy the mobile field guns and howitzers hidden in the gullies and nullahs (invisible from the ships) on the Asian shore and to the east of Achi Baba. The Boers, and later, the Japanese, had shown how difficult it is to locate well-concealed guns. Even when sea- and aero-planes had seen and signalled the whereabouts of the hidden guns, the ships could only fire at the flashes and at most hit some of the gunners; if their fire became too accurate the gunners would retire to their shelters, or withdraw their guns to new hidden emplacements. These hidden guns, firing continually upon the mine-sweepers, made the clearing of the mine fields towards the Narrows a slow and bloody task. On the 18th March, the ships developed a fierce fire upon the shore defences, and in the midst of the engagement the Turks floated some large mines upon the attacking ships and by these means sank three battleships, one French, two English, the French ship with all her crew.