 His father, Louis, was an engineer and businessman, whose company — Kabelwerke Dr. Cassirer & Co. — manufactured telegraphic cables, and was eventually taken over by Siemens.In 1895 he married Lucie Oberwarth.In 1901 Cassirer visited Julien Leclercq's retrospective of Van Gogh's work, and later that year he organized the inclusion of five Van Gogh canvases in the May show of the Berlin Secession.