(b) Their guns, however heavy, would not be overwhelmingly successful against temporary field works and gun emplacements.
(c) Their officers, unable in the first place to locate the guns hidden on the shore, would be unable to observe the effect of their fire, and therefore unable to direct it, and this disadvantage would become greater as the ships advanced within the channel and became shut in by the banks.
(d) They would be unable to enter the channel until the waters had been dragged for mines by mine sweepers. The batteries of field guns hidden on the coast would perhaps be sufficient to stop the progress of the mine sweepers. If not, floating mines, alongshore torpedo tubes, and the accurately ranged and directed fire of heavy howitzers would perhaps sink the ships of war as they advanced.
(e) A ship, if damaged, would be five hundred miles from any friendly dock and seven hundred miles from any friendly arsenal. Replenishments of ammunition, fuel, food and water would have to be brought to the attacking fleet across these distances of sea, past many islands and through one or two channels well suited to be the lurking grounds for enemy submarines.
On the other hand, there was the possibility that the heavy naval guns would make the field works untenable, that observers in aeroplanes and seaplanes would locate, range and observe the fire upon the hidden batteries, that thus the mine sweepers would be able to clear a passage up the Straits without undue interruption, and complete the task demanded of them without military assistance.
Before operations could be begun by the Allied fleets it was necessary to secure some harbour, as close as possible to the Straits, to serve as what is called an advanced or subsidiary base, where large stores of necessaries, such as fuel and munitions, could be accumulated for future use by the ships engaged.
The port of Mudros, in Lemnos, was selected as this subsidiary base. This great natural harbour, measuring some two by three miles across, provides good holding ground in from five to seven fathoms of water for half the ships in the world. Two islands in the fairway divide the entrance into three passages, and make it more easy for the naval officers to defend the approaches. It is a safe harbour for ocean-going ships in all weathers, but with northerly or southerly gales, such as spring up very rapidly there in the changeable seasons of the year and blow with great violence for some hours at a time, the port is much wind-swept and the sea makes it dangerous for boats to lie alongside ships. Mudros itself, the town from which the port is named, is a small collection of wretched houses inhabited by Levantines, who live by fishery, petty commerce, and a few olive gardens and vineyards. It has a cathedral or largish church, and a small wooden pier, without appliances, for the use of the native boatmen. The town lies to the east of the harbour, on some rising ground or sand which stands up a little higher than the surrounding country. Behind it, rather more than a mile away, are barren hills of some 800 or 900 feet. The port is ringed in with these hills; it looks like a great extinct crater flooded by the sea. Over the hills in fair weather the peaks of Samothrace can be seen. When the spring flowers have withered the island is of the colour of a lion's skin. Its only beauty then is that of changing light.
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.