Trained at the Royal Danish Academy of Fine Arts in Copenhagen, he showed his works at important exhibitions in the 1900s.

[2] As a boy he revealed a talent for drawing,[2] and attended the Academy of Gustav and Sophus Vermehren from 1896 to 1902, under the tutelage of Frants Henningsen.

After completing studies there, he enrolled at Kristian Zahrtmann’s school from 1902 to 1904, where he was exposed to an avant–garde art scene and was taught color and form processing.

[6] His paintings frequently draw subjects from mythology or the Bible and mix traditional and modern styles, with classical outline and geometric composition holding figures which border abstract art.

[3] André Salmon published after his death in Paris a collection of ten of Hartmann’s engravings together with an introduction and a biographical notice.