The Type 704A Rhön class tankers are replenishment oiler used by the German  Navy to provide underway replenishment for its ships  at sea.
Ships of the class
 A 1442 Spessart
A 1443 Rhön
 Originally the ships were built for Libya as Okene  (Rhön) and Okapi (Spessart). Rhön and Spessart are names of forests (small mountain  ranges) in Germany.
Spessart was originally built for civilian service by Kröger  of Rendsburg  in 1974. On 5 September 1977 she was commissioned into the Deutsche  Marine, based at Keil.
On 29 March 2009, as she was taking part in Operation Atalanta, Spessart was attacked by  a 7-man pirate boat.  In addition to the regular 40-man civilian crew, Spessart  carried a 12-man security detail which exchanged small arm fire with the  pirates, and repelled the assault.  The frigates HrMs De Zeven Provinciën,  HS Psara, SPS Victoria and the USS Boxer intervened and captured the pirates  after a few hours of chase.
Fgs Rhön is seen here arriving at Leith