He immigrated to Philadelphia, Pennsylvania in 1783, purchased land from Zephaniah Platt, and settled in what is now Plattsburgh, New York.
He was active in the lumber business, owned several stores, and was a successful fur trader and potash manufacturer.
As a result of their shared interest in the fur business, Sailly formed a longstanding friendship with John Jacob Astor.
During the War of 1812 Sailly was appointed keeper of the public stores, a position that gave him responsibility for all government warehouses in upstate New York.
in addition, he provided U.S. commanders, including James Wilkinson, intelligence about the Champlain Valley and British troop activities in New York and southern Canada.