Important German painter. Dettmann was educated at the academy in Berlin from 1884 to 1889, where he himself became a teacher in 1895. Immediately after his studies, he made a trip abroad that took him to Paris, London and the Netherlands. Dettmann was greatly influenced by Max Liebermann and the French Impressionists. Initially, Dettmann painted landscapes in the vicinity of Berlin and along the North and Baltic Sea coasts. There are also some genre scenes from the 1990s by him, he records the lives of fishermen and farmers, and he frequently made illustrations for magazines. He was an excellent watercolorist who achieved great fame in this field. From the late 1990s, Dettmann devoted himself to monumental painting and designed and painted wall decorations in public buildings, depicting mythological, religious, social or nationalistic subjects.