UB-148 at sea, a U-boat similar to UB-123.
History
German Empire
Name	UB-123
Ordered	6 / 8 February 1917[1]
Builder	AG Weser, Bremen
Cost	3,654,000 German Papiermark
Yard number	296
Laid down	13 July 1917[2]
Launched	2 March 1918[3]
Commissioned	6 April 1918[3]
Fate	Sunk 19 October 1918[3]
General characteristics [3]
Class & type	Type UB III submarine
Displacement	512 t (504 long tons) surfaced 643 t (633 long tons) submerged
Length	55.85 m (183 ft 3 in) (o/a)
Beam	5.80 m (19 ft)
Draught	3.72 m (12 ft 2 in)
Propulsion	2 × propeller shaft 2 × Körting four-stroke 6-cylinder diesel engines, 1,050 bhp (780 kW) 2 × Siemens-Schuckert electric motors, 780 shp (580 kW)
Speed	13.9 knots (25.7 km/h; 16.0 mph) surfaced 7.6 knots (14.1 km/h; 8.7 mph) submerged
Range	7,280 nmi (13,480 km; 8,380 mi) at 6 knots (11 km/h; 6.9 mph) surfaced 55 nmi (102 km; 63 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	50 m (160 ft)
Complement	3 officers, 31 men[3]
Armament	5 × 50 cm (19.7 in) torpedo tubes (4 bow, 1 stern) 10 torpedoes 1 × 10.5 cm (4.13 in) deck gun
Service record
Part of	III Flotilla 22 June – 19 October 1918
Commanders	Oblt.z.S. Robert Ramm[4] 6 April – 19 October 1918
Operations	2 patrols
Victories	1 merchant ship sunk (2,646 GRT) 1 merchant ship damaged (4,095 GRT) 3 merchant ships taken as prize (3,530 GRT)

SM UB-123 was a German Type UB III submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. She was commissioned into the German Imperial Navy on 6 April 1918 as SM UB-123.^{[Note 1]}

She torpedoed and sunk Leinster, a vessel operated by the City of Dublin Steam Packet Company on 10 October 1918, shortly after the new parliamentary based German Government under Max von Baden had asked U.S. President Woodrow Wilson to negotiate an armistice.

Leinster went down just outside Dublin Bay. Over 500 people perished in the sinking – the greatest single loss of life in the Irish Sea.

UB-123 struck a mine at the North Sea Mine Barrage on 19 October 1918, all 36 crew members died in the event.^[3]

Construction

She was built by AG Weser of Bremen and following just under a year of construction, launched at Bremen on 2 March 1918. UB-123 was commissioned later the same year under the command of Oblt.z.S. Robert Ramm. Like all Type UB III submarines, UB-123 carried 10 torpedoes and was armed with a 10.5 cm (4.13 in) deck gun. UB-123 would carry a crew of up to 3 officer and 31 men and had a cruising range of 7,280 nautical miles (13,480 km; 8,380 mi). UB-123 had a displacement of 512 t (504 long tons) while surfaced and 643 t (633 long tons) when submerged. Her engines enabled her to travel at 13.9 knots (25.7 km/h; 16.0 mph) when surfaced and 7.6 knots (14.1 km/h; 8.7 mph) when submerged.

Summary of raiding history

Date	Name	Nationality	Tonnage[Note 2]	Fate[5]
16 July 1918	Anine	Denmark	1,299	Captured as prize
16 July 1918	Constantin	Denmark	831	Captured as prize
16 July 1918	Hjortholm	Denmark	1,400	Captured as prize
10 October 1918	Leinster	United Kingdom	2,646	Sunk
16 October 1918	Caloria	United States	4,095	Damaged

References

Bibliography