Map of the Dardanelles.
You have heard how Admiral Hornby's fleet threaded the Dardanelles in 1878 without firing a shot. Now let me tell you very briefly how a British squadron forced its way through the straits in spite of strong resistance. In the year 1807, when we alone of all the European nations were holding out against the French, it was thought that if a British fleet were sent to Constantinople the Turks might be forced to break with Napoleon. So a powerful squadron under Admiral Duckworth sailed for the Dardanelles, with orders to demand the surrender of the Turkish fleet. If the demand was refused, he was to bombard Constantinople. Those were the days of sailing ships, and it was not easy to get men-of-war and frigates up the narrow winding waters, where the winds were irregular and the currents were baffling. The "castles" at the entrance and the forts at the Narrows opened fire on the ships; but little harm was done, and they passed through and anchored off Constantinople. It now seemed likely that under the muzzles of British guns the Sultan would give way. The French agents, however, persuaded him to "play for time," so that heavy batteries might be set up on the shores of the straits, and Duckworth's ships might be bombarded as they tried to return to the Mediterranean. Duckworth, you will notice, was in a very tight place. He was cut off from the open sea, and he could obtain no fresh supplies of food, water, or ammunition. It was clear that when his stores were exhausted he would be at the mercy of his enemies. So, before he could come to any agreement with the Sultan, he was forced to retire. His ships sailed slowly across the Sea of Marmora, and when the Narrows were reached the Turkish batteries opened fire with huge balls of marble, said to be hewn out of columns found amidst the ruins of Troy. One enormous stone shot cut the mainmast of the flagship in two; a second, that hit another vessel, knocked three gun ports into one, and killed or wounded sixty men. Finally, by good luck, the ships reached the open sea in safety. All on board were convinced that the experiment was too risky to be repeated.
Our greatest sailor, Nelson, always believed that strong, heavily armed forts could resist the attack of ships. When he was asked to reduce certain forts in Corsica by means of gun fire, he pointed out that stone walls were stronger than wooden walls, and that red-hot cannon balls from the guns of the forts might set his ships on fire. Since his day wooden walls have been replaced by armour plate, and red-hot shot by high-explosive shells. Nevertheless it is still true that shore batteries are more than a match for the heaviest armed battleships afloat. Of course, weak or badly-manned forts have been overcome by the guns of ships, as in the case of those at Alexandria, which were silenced by a British fleet in 1882; but as a rule ships run a great risk in attacking forts at close range, and are more than likely to come off second best.
While a fort can only be put out of action by gun fire, a ship can be sunk not only by gun fire, but by mines or torpedoes. Forts can be strengthened to almost any extent, and protected by earthworks of all kinds, but there is a limit to the thickness and weight of the armour plate with which ships can be clad. Further, while shore batteries can be so hidden that they cannot be detected even from aeroplanes, a ship in action is in full sight of the fort, and is thus a good target. Then, again, hits made on the outer slopes of forts do but little damage. The only hits that really count are those which destroy or dismount guns, and such "direct hits" are few and far between. On the other hand, every shot that hits the ship is bound to tell, and the ship may be put out of action without a single gun being hit. You must also remember that while the fortress gunner is aiming at a wall twenty or thirty feet high and a hundred feet long, the ship's gunner can only fire at a low mound, or at a battery not more than four and a half feet in height.
Even more difficult is the task of a ship's gunner when he is aiming at forts or batteries on high ground. It is not easy for a naval gun to bring an effective fire to bear on a target at a high level above the sea. Batteries on rising ground are difficult to reach, and when they are "spotted" they can be shifted to other positions, in which case the ship's gunners have to find the range all over again. When the shells from the ship's guns strike the ground they throw up columns of dust, and it is difficult for observers on board the ship or in the air to see exactly where the shells fall; but shells from the forts or land batteries drop into the sea, and throw up fountains of water which are clearly visible, and enable the observers on land to discover and set right all errors of range.
A ship attacking a fort from the sea may silence it for a time; but when the ship draws off, as it is bound to do, the fort may be repaired and new guns may be mounted. Unless a landing-party goes ashore and utterly destroys the fort, there is no guarantee that the ship's work will not have to be done all over again. Even if forts are blown up, land batteries can be established, and resistance can be continued. Without land forces to occupy the shores on which the forts are situated, no really lasting result can be obtained by the ships.
Now that you understand the disadvantages under which a fleet attacks forts, you will naturally ask why the British Government only sent ships to break down the defences of the Dardanelles. Why was not an army landed on the Gallipoli peninsula, to get behind the forts, or to attack them in the rear while the ships bombarded them from the sea? In the first weeks of February we were not ready to fit out and send a sufficiently strong army to the Gallipoli peninsula. Why, then, were the naval attacks not postponed until the army was ready? Probably it was thought that if we hastened to show our strength in Near Eastern waters Greece, Bulgaria, and perhaps Rumania, might be won over to our side, or, at least, persuaded to turn a deaf ear to the tempting voice of the Kaiser. Further, some of the rulers of our navy really believed that the armament of our warships was now so powerful that the straits could be carried by gun fire alone. The idea of our Admiralty was to silence the forts at the entrance to the straits, then with a fleet of mine-sweepers from the North Sea to clear the inner waters so that warships could steam sufficiently near to the forts at the Narrows to concentrate a fierce fire on them. When they were silenced the ships would dash through.
But even supposing the forts could be thus silenced, and our warships could slip through the straits, what then? So long as the Turks held the shores they could repair the damage to their forts, mount new batteries, strew the waters with mines, and take a heavy toll of our ships when lack of supplies forced them to return. Those who planned this naval attack probably thought that the Turks would give in as soon as Constantinople was shelled. But such a happy ending to the adventure was very doubtful.