This was one of the original areas of the Burnetsfield Patent in the province of New York, where in 1722-1723, Governor Burnet granted Palatine German immigrants leases to purchase land from the Mohawk, one of the powerful nations of the Iroquois Confederacy. It was the first land sold to Europeans west of Schenectady. During the 18th-century warfare in the valley, the village was attacked by French and Iroquois forces during the French and Indian War (Seven Years' War), and many women and children were taken to Canada as captives.
On September 17, 1778 Mohawk Indian chief and British Loyalist leader Joseph Brant leads a force of 150 Iroquois Indians and 300 British Loyalists under the command of Captain William Caldwell in a surprise attack on the area of German Flats, New York. German Flats, now known as Herkimer, New York, was left virtually undefended by Patriot troops prior to the raid.
The Indian and Loyalist raiders captured hundreds of head of cattle and sheep before setting fire to every house, barn and mill in German Flats. Despite the complete destruction of the town, including 63 houses, 57 barns, three gristmills and one sawmill, only three men were killed. The day before, four Patriot scouts had run into the Loyalists while on reconnaissance. Though only one, Adam Helmer, survived the encounter, he was able to run the nine miles back to the village of German Flats to warn the residents. As a result, the vast majority of the town's people was able to seek safety in the area's forts, Herkimer and Dayton, and survived the destruction of their town.
The town was set apart in the now defunct Tryon County, which was broken up into Montgomery and other counties after the Revolutionary War. It was established as a town in 1788 before the formation of Herkimer County. Previous to the establishment, the area that was to become the town had also been called German Flatts.
In 1791, when Herkimer County was established, German Flatts was one of the three original towns. Three new towns were created from German Flatts in 1792: Frankfort, Litchfield, and Warren. Another part of German Flatts was used in 1829 to form part of the Town of Little Falls.