Nicholas was the oldest son of Johan Jost and Katherine. His first military command was at Fort Herkimer in 1757. By 1775 he was Colonel of the first battalion, Tryon County Militia. He was commissioned Brigadier General of the Tryon County Militia on September 6, 1775. General Herkimer was mortally wounded while commanding the milita at the Battle of Oriskany on August 6, 1777. His brother Johan Jost was among the loyalists fighting with the British forces at Oriskany and the siege of Fort Stanwix.