He is best known for his historical novels, particularly:
* "Die letzten Ritter" (The Last Knights), a romantic novel about the last days of the Holy Roman Empire.
* "Die Kreuzfahrer" (The Crusaders), a historical novel about the Crusades.
He also wrote:
* "Wilhelm der Eroberer" (William the Conqueror), a biography of William the Conqueror.
* "Die Geschichte des deutschen Volkes" (The History of the German People), a multi-volume history of Germany.
However, his works are largely forgotten today, overshadowed by other more famous historical novelists of his time.