Sagard is first mentioned in 1250 as Zagard. The name of the municipality of Sagard comes from the Slavic and means something like "stockade" or "fortified settlement". This points to a Slavic burgwall from the 12th century that used to be here, but which has been levelled.

Around 1750, there were the beginnings of a health resort. In 1795, the pastor Heinrich Christoph von Willich, and his brother, the country doctor Dr. Moritz von Willich, opened a Spring, Bathing and Leisure Institute. The bathing facility lasted until about 1830. Today the Historic Brunnenaue Park recalls the former idyllic spa park with its promenades, fountains and bath houses.