Papers : 1755-1886.

Christian Daniel Claus (1727-1787) was born into a prominent family at Boennigheim in southwestern Germany and emigrated to New York in 1748. His interest in Indigenous languages led to the compiling of a vocabulary of Indigenous words and later to a position as a lieutenant in the Indian Department and a deputy secretary of Indian Affairs under Sir William Johnson. During the Seven Years War, he acted as an interpreter and diplomat at conferences and negotiations with Indigenous peoples. In 1760 Claus was named deputy superintendent of the Canadian Indians and was based in Montreal. He accompanied St. Leger on his ill-fated expedition to the Mohawk Valley in 1777 in his capacity as superintendent of the Canadian Indians. After Burgoyne's defeat at Saratoga, the Loyalist cause in the Upper Hudson was virtually all but lost and the Claus family fled to Canada.

In 1778 Claus was appointed deputy agent for the Six Nations in Canada and at the end of the Revolution helped supervise the settlement of several Indigenous groups in what is now Ontario, Canada. He died in England while trying to obtain compensation for the losses he suffered during the American Revolution.

His son William Claus (1763-1826) was also associated with the Indian Department, achieving the rank of deputy superintendent in 1799. He was a member of the Legislative Council of Upper Canada, 1812-1825, and of the Executive Council, 1818-1824.

The Claus family had strong connections with the Johnson family, Daniel Claus having married Ann (Nancy), the daughter of Sir William Johnson in 1762.