The man potrayed on this photography is king Frederik 7. of Denmark. His reign lasted from 1848 until 1863. It appears to me that he is wearing a galla uniform from the royal danish guards. The photo was probably taken in this period. Also, Frederik 7. was the last king from the Oldenborg dynasty. Despite of his obesity, he was a beloved king, known as the victor of the three years war, and also the king who allowed the establisments of democratic institutions in Denmark.
The uniforms worn by danish soldiers in the war of 1864 looked pretty much like the standard union infantry uniforms of the american civil war.