In shallow waters — and the E Class could descend to over 200 feet — the commanders had no fear of flooding their tanks entirely and of lying on the bottom so long as the air in the boat remained reasonably fresh — a period of some twenty hours. As they were not then moving there was still enough power in their accumulators to drive them to the surface again. The submarine’s time of greatest danger was, of course, during the three or four hours when it was obliged to cruise about on the surface to replenish its batteries.
At Gallipoli these submarines were faced with an objective which was entirely new and fantastically dangerous. If they could once get through to the Sea of Marmara they knew that they could do pretty much what they liked with the Turkish shipping, more particularly with the vessels that were bringing down reinforcements and supplies to Liman’s army on the peninsula. But how to get there, how to penetrate the Dardanelles?
The straits were swept all night by searchlights, and as soon as a submarine surfaced, as it was practically bound to do in the course of the forty-mile journey, it was not only fired on but ran the risk of being caught by the various currents that set towards the shore. Ten lines of mines off Kephez Point had to be negotiated, and beyond these there were the Narrows, under a mile wide, with guns on either side and patrol boats on the watch. There was another hazard: a stratum of fresh water about ten fathoms deep poured down the Dardanelles from the Sea of Marmara, and it was of much lighter density than the salt water below. This made a kind of barrier in the sea, and as they passed through it the submarines were thrown violently out of control. It was not unlike the experiences of the first supersonic aircraft when they met the sound barrier in the sky; no one could make out why this strange, deadly disturbance should occur, and the commanders were forced to rise to the surface where they at once came under the fire from the enemy batteries on the shore.
Up to the time of the landing every attempt to force the Narrows had failed, and even the Australian E2 was to last only a few days before she was caught on the surface and sunk. A French submarine, the Joule, was destroyed before she even reached Chanak. Yet the exploit still seemed possible, and the young commanders of the E Class submarines who came out from England during April were eager to try again. Many of them had fought under Roger Keyes’s command in the North Sea during the early months of the war, and their morale was very high. They believed they had only to try new tactics and they would get through.
For the German U-boats the problem at Gallipoli was quite different. Their target — and it was a superb target, almost a sitting duck — was the British battle fleet cruising along the shore of the peninsula in the open Ægean, and they were withheld from it not by the Narrows but by the wide expanse of the Atlantic and the Mediterranean. In April there was no German U-boat at Constantinople and none in the Mediterranean. The only way for the Germans to reach the scene of action was to sail round northern Europe and enter the Mediterranean through the Straits of Gibraltar; and this meant running the engines until almost the last ounce of fuel was gone. There was, it was true, a scheme for sending small U-boats in section by rail to Pola on the Adriatic coast, but nothing had come of this as yet.
And so at the opening of the campaign both sides were baulked in their undersea offensive. Each could see the prize plainly before it: for the British it was the helpless Turkish shipping in the Marmara, for the Germans the unprotected Allied battleships in the Ægean; and neither so far had been able to strike.
But now, at the end of April, there began a series of events which were to alter the whole character of the campaign. On April 25, the very day of the landing, Lieut.-Commander Otto Hersing, in the German U-boat 21, set out from Ems on the long journey around the north of Scotland for the Mediterranean. Two days later at Gallipoli, Lieut.-Commander Boyle, in the British E 14, slipped quietly into the Dardanelles and headed for the Narrows. From this moment both the Allied Fleet and the Turks on Gallipoli were in extreme danger.
Boyle had the idea of going through the Dardanelles on the surface under the cover of darkness, and he set off at two in the morning. He had not gone very far, however, before the Turkish searchlights and guns drove him down to a depth of ninety feet, and he continued there until he judged that he had passed under the Kephez minefield. Then he came up to twenty-two feet, intending to make the actual passage of the Narrows with his periscope raised. The disadvantage of this manœuvre was that the periscope made a distinct wash on the sea, and there was a desperate half-hour when the enemy guns around Chanak got his range. At one stage the crew of a Turkish patrol boat were grabbing at the periscope whenever Boyle brought it to the surface for a few seconds to see where he was going. Yet he got away, and soon after dawn came up unscathed in the Sea of Marmara. The passage had taken six hours.
For the next three weeks the E 14 cruised about at will. Her greatest success was the sinking of an old White Star liner that was bringing down from Constantinople 6,000 troops who were to join in the battle on the Cape Helles front. There were no survivors. It was a bigger victory than anything that had yet occurred on land, and there was immense elation in the Allied Fleet when Boyle came safely out again into the Ægean on May 18. Now at last they had found a way through. Admiral Guépratte had in the meantime lost a French submarine in the mysterious barrier in the straits, but that did not prevent him from congratulating the British; he sailed his flagship round the E 14 with his band playing Tipperary and the British national anthem.
Another submarine, the E 11, was waiting to take the E 14’s place in the Marmara, and her young captain, Lieut-Commander Nasmith, dined aboard the flagship on the night of May 18 with de Robeck, Keyes and Boyle. It was an animated party. Boyle had been recommended for an immediate award of the Victoria Cross. Keyes, who was still chafing at the withdrawal of the Queen Elizabeth and at the latest refusal of the Admiralty to allow the Fleet to resume its attack on the Narrows, thought he had begun to see a ray of light at last. Having heard Boyle’s story, Nasmith set off that same night, and sixteen hours after leaving the Admiral’s dining-table he was resting on the bottom of the Sea of Marmara. Unknown to anyone he had formed a plan which was more daring than anything which had been attempted before: a direct attack on Constantinople itself.
His first act on coming to the surface near the town of Gallipoli was to seize a Turkish sailing vessel and lash her to the E 11’s side, so that she would act both as a disguise and a decoy. When after several days no target appeared he cast off this Trojan sea-horse and steamed directly up the Marmara.
On May 23 he sank a Turkish gunboat and several other smaller craft, and then on the following day he fell in with the Nagara, a transport that was making its way down to the Dardanelles. There was an American journalist on board the Nagara, Raymond Gram Swing of the Chicago Daily News, and he says he was on deck that morning chatting to a Bavarian doctor. Boyle’s exploits of the previous weeks had become known in Constantinople, and Swing had just remarked to the doctor, ‘It’s a fine morning for submarines,’ when he paused, gazed out to sea in astonishment, and added, ‘And there’s one.’ E 11 broke the calm surface very gently about a hundred yards away, and four men appeared on the conning tower. One of them in a white sweater (it was Nasmith), used his cupped hands as a megaphone: ‘Who are you?’
‘I’m Swing of the Chicago Daily News.’
‘Glad to meet you, Mr. Swing, but what I mean is what ship is that?’
‘The Turkish transport Nagara.’
By now the ship’s crew were in a state of extreme alarm, some coursing about the deck, others, with their fezzes still on their heads, jumping into the sea.