U-23 may refer to one of the following German submarines:
Germany, officially the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, and the Alps to the south. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, France to the southwest, and Luxembourg, Belgium and the Netherlands to the west.
- SM U-23 (Germany), was the lead ship of the Type U 23 class of submarines; launched in 1913 and served in the First World War until sunk on 20 July 1915
- During the First World War, Germany also had these submarines with similar names:
- SM UB-23, a Type UB II submarine launched in 1915 and interned in Spain 29 July 1917
- SM UC-23, a Type UC II submarine launched in 1916 and surrendered on 25 November 1918
The UB II type submarine was a class of U-boat built during World War I by the German Imperial Navy. They were enlarged from the preceding type UB I and were more effective vessels. The boats were a single hull design with a 50-metre maximum diving depth and a 30-45 second diving time. In 1915 and 1916, 30 were built at two different shipyards.
SM UC-23 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy during World War I. The U-boat was ordered on 26 August 1915 and was launched on 29 February 1916. She was commissioned into the German Imperial Navy on 17 July 1916 as SM UC-23. In 17 patrols UC-23 was credited with sinking 45 ships, either by torpedo or by mines laid. UC-23 was surrendered at Sevastopol on 25 November 1918 and broken up at Bizerta in August 1921.
Type UC II minelaying submarines were used by the Imperial German Navy during World War I. They displaced 417 tons, carried guns, 7 torpedoes and up to 18 mines. The ships were double-hulled with improved range and seakeeping compared to the UC I type.
- During the First World War, Germany also had these submarines with similar names:
- German submarine U-23 (1936), a Type IIB submarine that served in the Second World War until scuttled on 10 September 1944
- German submarine U-23 (S172), a Type 206 submarine of the Bundesmarine that was launched in 1974 and sold after decommissioning to Columbia where she serves as ARC Intrépido.
SM U-23 was one of the 329 U-boats serving in the Imperial German Navy in World War I.
World War I, also known as the First World War or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as "the war to end all wars", it led to the mobilisation of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history. It is also one of the deadliest conflicts in history, with an estimated nine million combatants and seven million civilian deaths as a direct result of the war, while resulting genocides and the 1918 influenza pandemic caused another 50 to 100 million deaths worldwide.
SM UB-23 was a German Type UB II submarine or U-boat in the German Imperial Navy during World War I. The U-boat was ordered on 30 April 1915 and launched on 9 October 1915. She was commissioned into the Imperial German Navy on 13 March 1916 as SM UB-23. The submarine sank 49 ships in 21 patrols for a total of 28,228 gross register tons (GRT). On 26 July 1917, UB-23 was badly damaged by a depth charge attack by HMS PC-60 off the Lizard; she put in at Corunna, Spain, on 29 July 1917 and was interned. On 22 January 1919 she was surrendered to France in accordance with the requirements of the Armistice with Germany, and she was broken up in Cherbourg in July 1921.
U-23 or U-XXIII may also refer to:
- SM U-23 (Austria-Hungary), a U-20-class submarine of the Austro-Hungarian Navy
SM U-23 or U-XXIII was a U-20-class submarine or U-boat built for and operated by the Austro-Hungarian Navy during the First World War. The design for U-23 was based on submarines of the Royal Danish Navy's Havmanden class, and was largely obsolete by the beginning of the war.
  | This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists. |