|Builder:||William Beardmore and Company, Dalmuir|
|Laid down:||15 July 1919|
|Commissioned:||25 October 1919|
|Fate:||Sunk, 18 October 1940|
|Class and type:||H-class submarine|
|Length:||171 ft 0 in (52.12 m)|
|Beam:||15 ft 4 in (4.67 m)|
H49 survived until World War II when she was sunk by depth charging by German patrol craft commanded by Wolfgang Kaden belonging to the 5th German anti-submarine flotilla off Texel, the Netherlands on 18 October 1940. There was only one survivor, Leading Stoker George William Oliver from Hartlepool. He was rescued by German trawlers and spent the rest of the war as a POW at Marlag M 
In the mid 1980s amateur divers who had violated H49's war grave status were prosecuted by the Dutch government.
Like all post-H20 British H-class submarines, H49 had a displacement of 440 tonnes (490 short tons) at the surface and 500 tonnes (550 short tons) while submerged. It had a total length of 171 feet (52 m), a beam length of 15 feet 4 inches (4.67 m), and a draught length of 12 metres (39 ft). It contained a diesel engines providing a total power of 480 horsepower (360 kW) and two electric motors each providing 320 horsepower (240 kW) power. The use of its electric motors made the submarine travel at 11 knots (20 km/h; 13 mph). It would normally carry 16.4 tonnes (18.1 short tons) of fuel and had a maximum capacity of 18 tonnes (20 short tons).
The submarine had a maximum surface speed of 13 knots (24 km/h; 15 mph) and a submerged speed of 10.5 knots (19.4 km/h; 12.1 mph). Post-H20 British H-class submarines had ranges of 2,985 nautical miles (5,528 km; 3,435 mi) at speeds of 7.5 knots (13.9 km/h; 8.6 mph) when surfaced. H49 was fitted with an anti-aircraft gun and four 21 inches (530 mm) torpedo tubes. Its torpedo tubes were fitted to the bows and the submarine was loaded with eight 21 inches (530 mm) torpedoes. It is a Holland 602 type submarine but was designed to meet Royal Navy specifications. Its complement was twenty-two crew members.
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