Career
Born in Langendorf, Germany, Rosner shipped to sea at age 16. Five years later, at the outbreak of World War I, he left his ship in Peru and went to work in a copper mine. After the war he came via Canada to the United States, married, and settled in New York as an undocumented immigrant.
He was largely self-taught as a painter and watercolorist.
At first his artistic activities were interspersed with voyages in the merchant service. Eventually, he applied himself to marine painting and illustration full time, basing his work on his experiences at sea, on photographs, and on his own substantial and well-informed research.