After one year of painting studies in Copenhagen, he enrolled at the Academy of Art in 1855. He failed to progress in the academy's system, but with financial support from his brother and business owner
Diderik Cappelen (1856–1935), he studied under
Hans Gude at the
Düsseldorf Academy He spent the years 1859 to 1863 travelling over
Western and
Southern Norway, and spent 1863 to 1864 in Düsseldorf again. He is associated with the
Düsseldorf school of painting. He then travelled home due to illness, moved to
Christiania where he sealed a deal to make paintings that the
Christiania Kunstforening would sell at auctions, securing a steady income. He spent the years 1867 to 1868 in
Karlsruhe before finally settling at
Majorstuen in 1869. He participated almost annually in the
Autumn Exhibit between 1883 and 1911, and held notable exhibitions in Christiania Kunstforening (1895, 1906, 1924, 1931), at the
1862 International Exhibition, the
Exposition Universelle of 1889 and in Munich in 1913. Nielsen was also decorated as a Knight, First Class of the
Royal Norwegian Order of St. Olav in 1890. The square
Amaldus Nielsens plass, which includes a
bust of Nielsen, was named after him. ==Personal life==