Fisher’s obsession with the need to conserve the best of the Royal Navy’s resources for what he saw as the decisive battle of the war, against the German High Seas Fleet, meant that the battleships allotted to force the Chanak Narrows, then support land operations at Gallipoli were all vintage specimens, pre-dreadnoughts, some of which had been commissioned in the early 1890s. They were ,however, adequate for use as floating batteries, although their main armament of four 12-inch guns proved almost useless for giving close fire support for the infantry ashore; they were essentially ship-smashers, high velocity guns whose armour-piercing shells followed a flat trajectory whereas close fire support requires guns that have the ability to lob their fire over natural obstacles. Thus, when the allied fleet tried to force the Straits on 18 March 1915 the Turks , on the advice of their German tutors, used mobile field howitzers which could attack the decks of the warships from a near-vertical angle. Together with the great Krupp guns installed in the fixed shore fortifications, this gave the defence a distinct advantage.

Minefields were laid in the Dardanelles immediately Turkey entered the war and were progressively thickened until, by early March 1915 a considerable mine sweeping effort was necessary. The resources available to Admiral Carden were totally inadequate; flotillas of trawlers manned by their peacetime crews, embodied in the Royal Naval Reserve. These were expected to face the full force of the Turkish defences as they used wire sweeps to tackle the successive minefields. In the teeth of the perennial current flowing down the Straits at about 4 knots, the trawlers, whose best speed in still water was no more than 8 knots, could not expect to make more than walking speed when deploying their sweeps. After several had been hit by shore fire their crews stated that they would not continue and even the addition of regular officers and Petty Officers failed to achieve success. The loss of three battleships on 18 March was due to mines - notably those laid secretly in Eren Keui Bay from the steamer Nusret - as well as the devastating fire of the shore batteries..

Once the fleet's task became that of providing fire support for the troops ashore,. battleships were anchored close offshore in this role. Their presence gave heart to the troops ashore but exposed them to attack. The first to be sunk was HMS Goliath, torpedoed with great loss of life by a Turkish gunboat at night in Morto Bay. By mid-May German U-boats were arriving in the Mediterranean after a long and perilous voyage, to be based in Austro-Hungarian naval ports in the Adriatic. One of these, the U21, torpedoed HMS Triumph, then HMS Majestic within 48 hours of each other, in full view of the dismayed troops ashore and to the jubilation of their opponents. After that the navy withdrew its battleships from close support of land operations. Fire support was now provided by cruisers, destroyers and monitors - shallow draught gunboats originally designed for operations in the coastal waters off the German coast.

Mention has been made of the achievement of the submarine B11 which penetrated the Turkish minefields in December 1914 to sink the elderly battleship Messudieh off Chanak. This gave great encouragement to the Royal Navy's hitherto discounted submarine branch. Fisher had earlier been a strong proponent of underwater warfare but his retirement in 1911 had allowed opponents with conservative views to starve the fledgling submarine branch of resources. Whilst Fisher, on his return to the Admiralty as First Sea Lord in 1914, was adamant that no modern surface ships could be spared for the Dardanelles, he readily agreed to send a flotilla of submarines and these were to perform outstandingly throughout the campaign. The first attempt to penetrate the minefields and enter the Sea of Marmara was made on 17 April by the E15, which was detected and sunk before reaching the Narrows; it was followed early on 25 April, the day of the Gallipoli landings, by AE2, Australian manned, which had a short but spectacular career in the Sea of Marmara before being scuttled. After this the Marmara became the submariners' hunting ground and it became almost impossible for the Turks to sustain their forces on the Gallipoli peninsula by sea as the British submarines established their supremacy; the names of their commanders - Boyle and Dunbar-Nasmith above all others - became legends. On several occasions their submarines penetrated Constantinople harbour, torpedoing ships at the entrance to the Bosphorus.

As Kitchener had forbidden Hamilton the services of the Royal Flying Corps. Hamilton's air support had to be provided by the Royal Naval Air Service whose pilots displayed remarkable initiative, pioneering the use of the torpedo bomber, using wireless telegraphy to direct and adjust the fire of the fleet's guns, and, through aerial photography, providing accurate battlefield mapping for the first time. With the arrival of more modern fighter aircraft the RNAS was able to secure air superiority and, once Bulgaria had entered the war, to attack strategic targets in that country, through whose territory ran the key railroad bringing military supplies and munitions to Constantinople from the arsenals of Germany .

Throughout 1915 the two former German warships, the Goeben and Breslau, had operated under their commander, Admiral Souchon, as part of the Ottoman fleet in the Black Sea. In 1918, however, they emerged into the Sea of Marmara on the assumption that the allies had withdrawn their capital ships following the evacuation of the peninsula. It was a disastrous sortie, however. After sinking a few smaller warships off the entrance to the Straits, both struck British mines. Breslau sank with great loss of life and the badly holed Goeben after beaching for emergency repairs, limped back to Constantinople where she remained until the end of the war.