William Johnson was a Major General in the British forces during the French and Indian War. His alliances with the Iroquois were significant to the war. As a reward for his services, Johnson received large tracts of land in what are now Hamilton and Fulton counties. In 1760 the Mohawks of Canajoharie gave Johnson a tract of about 80,000 acres north of the Mohawk River. This was one of several large tracts of land that Johnson acquired from the Mohawk and Iroquois using his position as a royal Indian agent.
In 1760 Johnson founded the City of Johnstown on this grant and he named the new settlement, originally called John's Town, after his son John. The county courthouse, built by Johnson in 1772, partly at his own expense, still stands today, as the oldest operating courthouse in New York.
Please visit http://cityofjohnstown.ny.gov/our-history/ for more information.