Settlers were attracted to this area, then part of Preston, by the rich land of the Pachaug River Valley. The first permanent settlement was founded near Pachaug about 1690 on land purchased from Owaneco, son of Uncas, the Mohegan Indian sachem. In 1713 the first saw and corn mills were operating in Hopeville, and July of that same year marked the opening of a grist mill built at "the falls." The hamlet that grew up there was named for Isaac Glasko, a famed ironworker. When Preston divided into two ecclesiastical societies in 1716, a meeting house was erected at Pachaug for the North Society, and Hezekiah Lord was the first minister. In 1771 Eliezer Jewett opened a saw mill on the Pachaug River, beginning the village of Pachaug City. This area, later named Jewett City, was annexed to Preston from Norwich in 1786. Desiring independence, the North Society petitioned the legislature and was separated from Preston in 1815. The newly formed town was named for Roger Griswold, a Federalist governor, and it was the last town incorporated under the old constitution of the State of Connecticut, the Charter of 1662.