Kapitänleutnant Walter Rumpel was her captain for her entire career.

[4] British Naval Intelligence (better known as Room 40):[5] monitored and recorded her activities.

She was attached to the 2nd Half Flotilla and carried out a patrol in the North Sea between 2 May and 6 May 1916, traveling to Hanstholm in company with SM U-70, escorted by two Zeppelins.

She fired two torpedoes at the British battleship HMS Warspite, but missed her.

[7] On 14 July the British submarine HMS H5 spotted U-51 leaving the Ems and torpedoed her.