The son of Commander Hans Kaas and Agatha Rodsteen nee Banner, Frederik Christian Kaas was born on 1 December 1725 at Rydbjerg near
Ringkøbing fjord. In 1748 he was granted leave to travel to Holland at his own expense for treatment of a wound on one cheek. He married his first wife, Susanne Jacoba Fabritius, in 1757 (she died 1762). In 1764, after a period of dubious health, he married his second wife, Christine Elisabeth Birgitte Juul. ==Service career and promotions==