# SM U-46

SM U-46 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-46 was engaged in the combat during World War I and took part in the First Battle of the Atlantic. After the war, she served in the Imperial Japanese Navy as O-2.

## Imperial German Navy

Ordered on 4 August 1914, U-46 was constructed at the Kaiserliche Werft in Danzig, Germany. Launched on 18 May 1915, she was commissioned on 17 December 1915.
Assigned to the III Flotilla, U-46 began her first war patrol on 29 March 1916. Remaining in the III Flotilla for the rest of the war, she conducted a total of 11 war patrols before the war ended on 11 November 1918 and was credited with sinking 51 merchant ships totaling 138,942 gross register tons and one auxiliary warship of 1,372 gross register tons and damaging one merchant ship of 7,378 gross register tons.
After the end of the war, she surrendered to Japan on 26 November 1918.

### Summary of raiding history

| Date | Name | Nationality | Tonnage | Fate |
| 29 September 1916 | Ravn | Norway | 1,260 | Sunk |
| 29 September 1916 | Sinsen | Norway | 1,925 | Sunk |
| 30 September 1916 | Hafnia | Norway | 962 | Sunk |
| 30 September 1916 | Hekla | Norway | 950 | Sunk |
| 4 October 1916 | Brantingham | United Kingdom | 2,617 | Sunk |
| 6 October 1916 | Erika | Russian Empire | 2,430 | Sunk |
| 9 October 1916 | Astoria | United Kingdom | 4,262 | Sunk |
| 11 October 1916 | Iolo | United Kingdom | 3,903 | Sunk |
| 16 December 1916 | Chassie Maersk | Denmark | 1,387 | Sunk |
| 16 December 1916 | Taki Maru | Japan | 3,208 | Sunk |
| 16 December 1916 | Gerda | Denmark | 775 | Sunk |
| 17 December 1916 | Bayhall | United Kingdom | 3,898 | Sunk |
| 19 December 1916 | Falk | Norway | 948 | Sunk |
| 23 December 1916 | Marques De Urquijo | Spain | 2,170 | Sunk |
| 25 December 1916 | Marie Pierre | France | 166 | Sunk |
| 27 December 1916 | Aislaby | United Kingdom | 2,692 | Sunk |
| 27 December 1916 | Goulfar | France | 259 | Sunk |
| 21 March 1917 | Hindustan | United Kingdom | 3,692 | Sunk |
| 23 March 1917 | Argo | Portugal | 1,563 | Sunk |
| 24 March 1917 | Montreal | France | 3,342 | Sunk |
| 1 April 1917 | Aztec | United States | 3,727 | Sunk |
| 3 April 1917 | Hesperus | Russian Empire | 2,231 | Sunk |
| 5 April 1917 | Benheather | United Kingdom | 4,701 | Sunk |
| 7 April 1917 | Fiskaa | Norway | 1,700 | Sunk |
| 15 May 1917 | Grosholm | Norway | 1,847 | Sunk |
| 17 May 1917 | Lewisham | United Kingdom | 2,810 | Sunk |
| 18 May 1917 | Llandrindod | United Kingdom | 3,841 | Sunk |
| 18 May 1917 | Penhale | United Kingdom | 3,712 | Sunk |
| 20 May 1917 | HMS Paxton | Royal Navy | 1,372 | Sunk |
| 22 May 1917 | Tansan Maru | Japan | 2,443 | Sunk |
| 24 May 1917 | Jersey City | United Kingdom | 4,670 | Sunk |
| 24 July 1917 | Brumaire | United Kingdom | 2,324 | Sunk |
| 24 July 1917 | Zermatt | United Kingdom | 3,767 | Sunk |
| 25 July 1917 | Peninsula | United Kingdom | 1,384 | Sunk |
| 25 July 1917 | Purley | United Kingdom | 4,500 | Sunk |
| 27 July 1917 | Begona No. 4 | United Kingdom | 2,407 | Sunk |
| 31 July 1917 | Shimosa | United Kingdom | 4,221 | Sunk |
| 22 October 1917 | Zillah | United Kingdom | 3,788 | Sunk |
| 24 October 1917 | Ilderton | United Kingdom | 3,125 | Sunk |
| 28 October 1917 | Baron Balfour | United Kingdom | 3,991 | Sunk |
| 4 November 1917 | Irina | Russian Empire | 2,210 | Sunk |
| 7 November 1917 | Obj | Norway | 1,829 | Sunk |
| 27 January 1918 | Andania | United Kingdom | 13,405 | Sunk |
| 31 January 1918 | Towneley | United Kingdom | 2,476 | Sunk |
| 1 February 1918 | Cavallo | United Kingdom | 2,086 | Sunk |
| 3 February 1918 | Lutece | France | 1,346 | Sunk |
| 5 February 1918 | Cresswell | United Kingdom | 2,829 | Sunk |
| 13 March 1918 | Crayford | United Kingdom | 1,209 | Sunk |
| 18 March 1918 | Atlantic Sun | United States | 2,333 | Sunk |
| 30 March 1918 | Stabil | Norway | 538 | Sunk |
| 25 May 1918 | Rathlin Head | United Kingdom | 7,378 | Damaged |
| 16 September 1918 | Tasman | United Kingdom | 5,023 | Sunk |
| 25 September 1918 | Gloire a Jesus | France | 60 | Sunk |

## Imperial Japanese Navy

Transferred to Japan after surrendering, the submarine was commissioned into the Imperial Japanese Navy in 1920 as O-2. Decommissioned in 1921, she was partly dismantled at the Kure Naval Arsenal in April 1921.
A photo of U-46 apparently at the time of transfer to Japan shows the submarine docked and flying the flag of the Imperial Japanese Navy over the flag of the Imperial German Navy.
Some sources claim that O-2 was scrapped in 1922. Other sources claim that in 1925, O-2 was rebuilt at Yokosuka Naval Arsenal to serve as a testbed for submarine salvage operations by the submarine salvage ship Asahi and foundered in the Pacific Ocean in a storm off the coast of Japan during her transfer voyage from Yokosuka to Kure on 21 April 1925, adding that an American merchant ship sighted her derelict hulk floating in the Pacific west of Oahu, Hawaii, on 5 August 1927, and that the hulk subsequently was scuttled.