From 1863-1866, he studied at Johan Fredrik Eckersberg"s academy of painting in Christiania (now Oslo), Norway.
John Hammerstad first served as an apprentice to a painter and decorator. Johan Fredrik Eckersberg, who lived from 1822 to 1870, was a representative of the late Romantic Düsseldorf school of painting. Hammerstad emigrated to the United States. in 1869.
Hammerstad was married to Agnes Klemp (1857-1948), daughter of Mr.
And Mistress Christian Klemp of Fredrikshald, Norway. They had four children and settled in Chicago, Illinois.
He was considered to have been the first professionalil trained painter of Norwegian birth in the Midwest. Starting in the 1870s, Norwegian-American interest in fine arts developed in urban immigrant centers including Chicago, Minneapolis, and Seattle.
He was primarily known as a landscape painter, but also occasionally depicted such subjects as buffalo and boats.
Many were sold to Chicagoans to adorn their Victorian homes. Work by Hammerstad is among the holdings at the Fine Art Gallery of Vesterheim Norwegian-American Museum in Decorah, Iowa.