When Britain committed to World War 1 in 1914, the E-class submarine formed the primary underwater fighting force. The group (built through three main production batches) ultimately numbered fifty-eight boats with the first examples introduced before the war in 1912 (E1 was launched during November of that year). The E-class proved a critical component to British naval operations during the entirety of the war - which ended with the Armistice of November 1918 - even though they had, by this time, been succeeded by the L-class during the conflict. The L-class went on to number twenty-seven of the seventy-three originally intended and these were in service from the period spanning 1917 to 1942. E-class boats were given up by 1922.
The E-class served with both the British and Australian Royal Navies with little difference between them during wartime. They succeeded the earlier D-class boats which were the first Royal Navy submarines to offer deep-water service - generally early boats were confined to coastal patrol work due to their simpler designs.
The outward design of the E-class was typical of submarines of the period - large, bulbous hull sides, a flat-topped walking deck and a general "whale-like" appearance greeted onlookers. The conning tower was short and squat while being seated near midships. Planes were featured along the sides of the forward hull and at the tail section. The walking deck ran from the extreme bow end along 3/4 of the boat's total length towards the stern. The submarine held a crew complement of thirty officers of submariners and dimensions included a length of 178 feet with a beam of 15 feet.
Armament varied between the first and second/third boat groups completed. Group 1 was given 4 x 18" (450mm) torpedo tubes with one fitted at the bow, one at the stern and the remaining pair in beam positions. Group 2 and Group 3 boats added a second launcher at the bow and carried a single 12-pounder deck gun for surface work. Aussie boats followed the Group 1 armament fit.
Group 1 boats were powered by 2 x Vickers diesel units of 800 horsepower (each) for surface travel and 2 x electric motors of 600 horsepower (each) for submerged work. Group 2 (and Group 3) relied on the same diesel output but were given improved electric motors of 840 horsepower (each). In either arrangement, the engine pairings drove two screws. Performance included a maximum surfaced speed of 15 knots with underwater travel able to reach 10 knots. Range was out to 3,000 nautical miles when making headway at 10 knots. Submerged travel range was drastically reduced to 65 nautical miles at 5 knot speeds.
Because of the rather infant technology featured in attack submarines of the time, surface travel was always a faster method than submerged travel (this being reversed with today's advanced submarine types). As such, the boats tended to spend much of their actual operating times on the surface of the water, propelled by their diesel engines as if a conventional surface boat. It was during these phases of service that the boats were their most vulnerable to enemy attack. Submerged travel was generally slow and only temporary, limited by the power available through the onboard battery stores and the build-up of dangerous CO2 gasses produced by the crew. When surfaced, the boats could recharge their batteries and expel gas.
The E-class had the fortune of being progressively improved throughout its service life as technological advances in the war, in turn, allowed for advances in submarine technology to be put to the test. This led to a prolonging of their time in frontline service. Several of the batches also served as dedicated minelayers beyond their intended attack roles.
Group 1 encompassed boats E1 through AE2 while Group 2 added E9 through E20. Group 3, the largest of the batches, introduced E21 through E56. Various boats of the class lost during their at-sea tenures - either run aground, scuttled, sunk by mines or enemy torpedoes for their time in the war. E7 and AE2 were both lost during the infamous Battle of Gallipoli (1915-1916). E22 was reworked to serve as an aircraft carrier and supported a pair of Sopwith "Baby" floatplanes but was eventually torpedoed near Great Yarmouth by a German submarine on April 25th, 1916. E49 was mined and sunk near Huney (Shetland Islands) on March 12th, 1917.
Because of the size of the class, many British builders were involved in their construction. Participants included Vickers, William Beardmore, Yarrow, John Brown and Armstrong Whitworth - some of these names being better associated with airplane-making during the conflict.