Imperial German U-Boat, UB-123
RMS Leinster (Royal Mail Ship) operated by the City of Dublin Steam Packet Company, served as the Kingstown- Holyhead mail boat.
She was torpedoed and sunk by German submarine UB-123 on October 10, 1918, while bound for Holyhead. She went down just outside Dublin Bay some 501 people perished in the sinking — the greatest single loss of life in the Irish Sea.
The UB-123 was lost in a minefield in the North Sea on her way back to Germany, on or about October 19, 1918. The bodies of her commander Oberleutnant zur See Robert Ramm and his crew of two officers and thirty three men were never recovered.
During WW-I UB-123 made 2 war patrols and had sunk 2 ships for a total of 6,221 tons and 3 ships taken as prize for a total of 3,530 tons.
Specifications, UB-123, type UB-III:
Acostal torpedo attack boat, was laid down on July 13, 1917, at A.G.Weser, Bremen; launched March 2, 1918; and commissioned April 6, 1918.
Displacement (srf/sub tons): 516/651
Dimensions (L*B*D meter): 55.30*5.80*3.70
Propulsion: 2*550hp diesel engines, 2*395hp electric motors for submergence, driving two shafts
Speed (srf/sub knots): 13.6/8.0
Range (srf/sub n/miles@knots): 9,040@6/54@4
Diving depth (feet): 246
Complement: 34 officers and enlisted
Torpedo: 4*bow torpedo tubes, 1*stern torpedo tubes, total of 10 torpedoes
Armament: 1*88mm main deck gun
The UB class was the back bone of the German Imperial Navy during World War I. Three types of boats were built under this class- 17 boats of the 142 ton type I (1914-1915), 30 boats of the 292 ton type II (1915-1916) and 95 boats were built in this type by 4 different shipyards- Vulcan, Hamburg, A.G.weser, Bremen, Blohm & Voss, Hamburgand Germaniawerft, Kiel, all between 1916-18.