HMS E7 was a Group 1 E class submarine built by HM Dockyard Chatham. The E class went on to become the most numerous British submarine in WW1 with 58 boats being built. Despite half that number being lost during the war, the E class formed the backbone of the British submarine fleet until they were replaced by the L class.
HMS E7 was laid down on No 7 slip on 30th March 1912. She was launched by Miss Anson, the daughter of the Admiral Superintendant at Chatham at the time, Rear Admiral Charles Anson on 2nd October 1913. She commissioned after fitting out at Chatham on 16th March 1914, under Lt-Cdr Fielmann. On completion, she was 178 ft long and 15ft 5" across the beam. She displaced 665 tons surfaced and 796 tons dived. She was armed with 4 18" torpedo tubes, one in the bow, one on each beam and one in the stern. She also carried a deck gun. She was manned by a crew of 30 men.
Model of an E class submarine. E7 would have been identical.
Cutaway diagram of HMS E9. E7 was almost identical
On the outbreak of WW1, she was stationed in Harwich, conducting patrols in Heligoland Bight, but was sent to the Sea of Marmara in June of 1915 to relieve HMS E14. By now, she had a new commander, Lt-Cdr Cochrane. On passing through the Dardanelles, she was fired at by a shore based torpedo crew and a Turkish destroyer made two attempts to ram her. She managed to get through unscathed and relieved HMS E14 on 30th June. Her patrol of the Marmara Sea was to last 24 days.
She immediately got stuck into the enemy, but her patrol did not start well. On 1st July, after having boarded an enemy steamer, Lieutenant Halifax and an Able Rating were badly burned in an engine room explosion aboard the enemy vessel. There was then an outbreak of dysentery aboard E7 with the boats remaining officers and a telegraphist coming down with it. Despite this, she continued her patrol, which went on to be spectacularly successful. Over the course of her 24-day patrol, she sank 5 enemy steamers and 16 sailing vessels. On 17th July, HMS E7 bombarded a railway cutting and succeeded in blocking the line. She then proceeded to Derinjie Burnu where she continued her railway-busting exploits by bombarding an ammunition train, destroying all 3 carriages. From there, she moved to Karu Burnu where she destroyed another train.
HMS E7 at sea
At the end of August she began her journey home, but on 4th September 1915, while attempting to pass under the Turkish anti-submarine nets at Nagara, one of her propellers became entangled. Her attempts to free herself did not pass unnoticed by the Turks and they soon started attacking the boat with bombs dropped from small boats. At the time, the German submarine UB-14 was undergoing repairs at Chanak. Her commander, none other than Oberleutnant zur Zee Heino von Heimburg, Prince Heinrich of Prussia, heard the explosions and decided to take a close look at what was going on. He and the U-Boat's cook went out in a small rowing boat to observe the action. On seeing that the Turks efforts were having no effect, von Heimburg decided to use a plumb-line in an attempt to find the British submarine. The line was repeatedly dropped until he felt it contact metal. von Heimburg then dropped a Turkish sinker mine with a shortened fuse right on top of E7. By the time this happened, E7 had been trapped in the net for 12 hours. The explosion was too close for comfort and with his crew running short of air, Lt-Cdr Cochrane realised the game was up. Once the confidential papers had been destroyed and the scuttling charges set, he ordered that E7 be surfaced to allow the crew to escape. After everyone was off the boat, the charges were set off and E7 went to the sea-bed for good. Between the explosions of HMS E7's scuttling charges and the Turkish shellfire coming from the shore, von Heimburg and his cook were lucky to escape themselves.
HMS E7's officers and crew were taken into captivity for the rest of the war. Lt-Cdr Cochrane however was determined not to be a prisoner for long. On his 2nd escape attempt, he stole a sailing boat and made it to Cyprus.
