|Shipyard||Kaiserliche Werft, Danzig (Werk 15)|
|Ordered||25 Nov 1910||Laid down||27 Oct 1911|
|Launched||8 Feb 1913||Commissioned||22 Oct 1913|
|start date unknown - 4 Mar 1917 Pola Flotilla
1 Aug 1914 - 5 Jun 1915 III Flotilla
5 Jun 1915 - end date unknown Constantinople Flotilla
4 Mar 1917 - 11 Nov 1918 III Flotilla
|Successes||36 ships sunk with a total of 79,005 tons.|
2 ships damaged with a total of 8,918 tons.
4 warships sunk with a total of 34,575 tons.
|Fate||22 Feb 1919 - Sunk in an accident in position 54.19N, 03.42W while on passage to surrender..|
On 5 September, 1914 the small British cruiser HMS Pathfinder was torpedoed and sunk in the North Sea by U 21. This was the first warship to be sunk by a German U-boat during the First World War.
There was another U 21 in World War Two|
That boat was launched from its shipyard on 31 Jul 1936 and commissioned into the Kriegsmarine on 3 Aug 1936. Take a look at the U 21 from WWII.