# List of Austro-Hungarian U-boats

The Austro-Hungarian Navy (Kaiserliche und Königliche Kriegsmarine, shortened to k.u.k. Kriegsmarine) built a series of U-boats between 1907 and 1918 to defend its coastline and project naval power into the Adriatic and Mediterranean Seas in wartime. With the establishment of the Austrian Naval League in September 1904 and the appointment of Vice-Admiral Rudolf Montecuccoli to the post of Chief of the Naval Section of the War Ministry in October that same year, the k.u.k. Kriegsmarine began a program of naval expansion befitting a Great Power. Montecuccoli immediately pursued the efforts championed by his predecessor, Admiral Hermann von Spaun, and pushed to greatly expand and modernize the Austro-Hungarian Navy. By the spring of 1905, Montecuccoli envisioned a modern Austrian fleet of 12 battleships, four armoured cruisers, eight scout cruisers, 18 destroyers, 36 high seas torpedo craft, and six submarines.
The Austro-Hungarian U-boat fleet during the First World War mainly consisted of German designs built under licence and purchased units transported by rail from Germany's northern shipyards to the Austrian ports on the Adriatic Sea. They served throughout the war against Italian, French and British shipping in the Mediterranean Sea with some success, losing 8 of the 28 boats in service in return. Following the end of the war in 1918, all Austrian submarines were surrendered to the Entente powers, who disposed of them individually. As both Austria and Hungary became landlocked in the aftermath of the war, no Austrian or Hungarian submarines (or any other naval vessels) have been commissioned since.
In some sources Austro-Hungarian U-boats are referenced with Roman numerals as a way to distinguish them from German U-boats with similar numbers, but the Austro-Hungarian Navy itself used Arabic numerals. There are gaps in the numbering for several reasons. One series of Austro-Hungarian U-boats under construction in Germany was sold and commissioned into the Imperial German Navy. In other cases, U-boats commissioned into the Imperial German Navy were temporarily assigned Austro-Hungarian numbers when they operated in the Mediterranean. One final reason, in the case of the unassigned U-13, was superstition.

## Austro-Hungarian U-boats
### Commissioned

| U-boat | Class | Launched | Commissioned | Fate | Notes |
| 01SM U-1 | 01U-1 class | 2 October 1909 | 15 April 1911 | Scrapped 1920 | |
| 02SM U-2 | 01U-1 class | 3 April 1909 | 22 May 1911 | Scrapped 1920 | |
| 03SM U-3 | 03U-3 class | 8 August 1908 | 12 September 1909 | Sunk 13 August 1915 | |
| 04SM U-4 | 03U-3 class | 20 November 1908 | 29 August 1909 | Scrapped 1920 | |
| 05SM U-5 | 05U-5 class | 10 February 1909 | 1 April 1910 | Scrapped 1920 | |
| 06SM U-6 | 05U-5 class | 12 June 1909 | 1 July 1910 | Scuttled 13 May 1916 | |
| 10SM U-10 | 10U-10 class | 29 January 1915 | 12 July 1915 | Mined 9 July 1918; scrapped 1918 | The former German SM UB-1 |
| 11SM U-11 | 10U-10 class | 4 April 1915 | 20 June 1915 | Scrapped 1920 | The former German SM UB-15 |
| 12SM U-12 | 05U-5 class | 14 March 1911 | 21 August 1914 | Sunk 12 August 1916 | Raised and scrapped end of 1916 |
| 14SM U-14 | 14U-14 class | 18 July 1912 | 1 June 1915 | Returned to France, 1919; scrapped 1929 | Captured French submarine Curie (Q 87) |
| 15SM U-15 | 10U-10 class | April 1915 | 6 October 1915 | Scrapped 1920 | |
| 16SM U-16 | 10U-10 class | 26 April 1915 | 6 October 1915 | Sunk | |
| 17SM U-17 | 10U-10 class | 21 April 1915 | 6 October 1915 | Scrapped 1920 | |
| 20SM U-20 | 20U-20 class | 18 September 1916 | 20 October 1917 | Sunk | Wreck raised in 1962; conning tower on display in Vienna |
| 21SM U-21 | 20U-20 class | 15 August 1916 | 15 August 1917 | Scrapped 1920 | |
| 22SM U-22 | 20U-20 class | 27 January 1917 | 23 November 1917 | Scrapped 1920 | |
| 23SM U-23 | 20U-20 class | 5 January 1917 | 1 September 1917 | Sunk 21 February 1918 | |
| 27SM U-27 | 27U-27 class | 19 October 1916 | 24 February 1917 | Scrapped 1920 | |
| 28SM U-28 | 27U-27 class | 8 January 1917 | 26 May 1917 | Scrapped 1920 | |
| 29SM U-29 | 27U-27 class | 21 October 1916 | 21 January 1917 | Scrapped 1920 | |
| 30SM U-30 | 27U-27 class | 27 December 1916 | 17 February 1917 | Went missing after 31 March 1917 | |
| 31SM U-31 | 27U-27 class | 28 March 1917 | 24 April 1917 | Scrapped 1920 | |
| 32SM U-32 | 27U-27 class | 11 May 1917 | 29 June 1917 | Scrapped 1920 | |
| 40SM U-40 | 27U-27 class | 21 April 1917 | 4 August 1917 | Scrapped 1920 | |
| 41SM U-41 | 27U-27 class | 11 November 1917 | 19 February 1918 | Scrapped 1920 | |
| 43SM U-43 | 43U-43 class | 8 April 1916 | 30 July 1917 | Scrapped 1920 | The former German SM UB-43 |
| 47SM U-47 | 43U-43 class | 17 June 1916 | 30 July 1917 | Scrapped 1920 | The former German SM UB-47 |

### Other

Submarines on which construction was begun but which were not completed or commissioned during World War I are included in this table.
| U-boat | Class | Laid down/Launched/Commissioned | Fate |
| U-48 | U-48 class | laid down, not launched or completed | scrapped at war's end |
| U-49 | U-48 class | laid down, not launched or completed | scrapped at war's end |
| U-50 | U-50 class | laid down, not launched or completed | scrapped at war's end |
| U-51 | U-50 class | laid down, not launched or completed | scrapped at war's end |
| U-52 | U-52 class | laid down, not launched or completed | scrapped at war's end |
| U-53 | U-52 class | laid down, not launched or completed | scrapped at war's end |
| U-101 | U-101 class | laid down, not launched or completed | scrapped at war's end |
| U-102 | U-101 class | laid down, not launched or completed | scrapped at war's end |
| U-103 | U-101 class | laid down, not launched or completed | scrapped at war's end |
| U-107 | U-107 class | laid down, not launched or completed | scrapped at war's end |
| U-108 | U-107 class | laid down, not launched or completed | scrapped at war's end |

## German U-boats operating under the Austro-Hungarian flag

After Italy had entered World War I by declaring war on Austria-Hungary on 23 May 1915, Germany felt treaty-bound to support the Austrians in attacks against Italian ships, even though Germany and Italy were not officially at war. As a result, German U-boats operating in Mediterranean were assigned Austro-Hungarian numbers and flags. In some cases the same Austro-Hungarian numbers were assigned to different German U-boats. After 28 August 1916, when Germany and Italy were officially at war, the practice continued, primarily to avoid charges of flag misuse. The practice was largely ended by 1 October 1916 except for a few large U-boats that continued using Austro-Hungarian numbers.
German U-boats under the Austro-Hungarian flag :
| Austro-Hungarian name | German U-boat name(s) |
| SM U-7 | SM UB-7 |
| SM U-8 | SM UB-8 |
| SM U-9 | SM UB-3 |
| SM U-18 | SM UC-14 |
| SM U-19 | SM UC-15 |
| SM U-24 | SM UC-12 |
| SM U-25 | SM UC-13 |
| SM U-26 | SM UB-14 |
| SM U-33 | SM U-33 |
| SM U-34 | SM U-34 |
| SM U-35 | SM U-35 |
| SM U-36 | SM U-21 SM U-47 |
| SM U-37 | SM U-32 |
| SM U-38 | SM U-38 |
| SM U-39 | SM U-39 |
| SM U-42 | SM UB-42 |
| SM U-44 | SM UB-44 |
| SM U-45 | SM UB-45 |
| SM U-46 | SM UB-46 |
| SM U-54 | SM UB-128 |
| SM U-55 | SM UB-129 |
| SM U-56 | SM UB-130 |
| SM U-57 | SM UB-131 |
| SM U-58 | SM UB-132 |
| SM U-60 | SM UC-20 |
| SM U-62 | SM UC-22 |
| SM U-63 | SM UC-23 SM UC-63 |
| SM U-64 | SM U-64 |
| SM U-65 | SM U-65 |
| SM U-66 | SM UB-66 SM UC-66 |
| SM U-67 | SM UB-67 |
| SM U-68 | SM UB-68 |
| SM U-69 | SM UB-69 SM UC-69 |
| SM U-70 | SM UB-70 |
| SM U-71 | SM UB-71 |
| SM U-72 | SM U-72 |
| SM U-73 | SM U-73 |
| SM U-74 | SM UC-34 |
| SM U-75 | SM UC-35 |
| SM U-77 | SM UC-37 |
| SM U-78 | SM UC-16 SM UC-38 |
| SM U-79 | SM UB-48 |
| SM U-80 | SM UB-49 |
| SM U-81 | SM UB-50 |
| SM U-82 | SM UB-51 |
| SM U-83 | SM U-63 SM UB-52 SM UC-20 SM UC-23 |
| SM U-88 | SM UC-24 |
| SM U-89 | SM UC-25 |
| SM U-92 | SM UC-73 |
| SM U-93 | SM UC-74 |
| SM U-94 | SM UC-52 |
| SM U-95 | SM UC-53 |
| SM U-96 | SM UC-54 |
| SM U-97 | SM UB-105 |
| SM U-99 | SM UC-103 |
| SM U-110 | SM UC-108 |
| SM U-133 | SM UB-133 |
| SM U-134 | SM UB-134 |
| SM U-135 | SM UB-135 |
| SM U-146 | SM UB-146 |
| SM U-147 | SM UB-147 |