Pachaug State Forest was established with a 1,011 acre land purchase from the Briggs Manufacturing Co. in Voluntown in 1928. In 1933, the first year the Civilian Conservation Corps began, Camp Lonergan was established in the Forest. As funding became available, the forest quickly grew, totaling 12,000 acres by 1937. The actions of the Resettlement Administration, in 1937, acquired an additional 9,000 acres and leased the land to the state for forest production. Eventually, this land was deeded to the state.
At present, Pachaug covers 26,477 acres in six towns, and is the largest state forest in Connecticut. The word "Pachaug" is derived from the Native American term meaning bend or turn in the river. Pachaug River, in the nine miles from its source at Beach Pond to its junction with the Quinebaug River, traverses approximately twice that distance in the course of its various windings and turns. Pachaug-Great Meadow Swamp was designated a National Natural Landmark in 1973 and is considered one of the finest and most extensive Atlantic white cedar swamps in Connecticut.
When the Europeans arrived, Pachaug Forest was tribal land of the Narragansett, Pequot, and Mohegan people. Wampanoag Sachem Metacom, also known as Metacomet or King Philip, the name given to him by the English, led an uprising of Wampanoag, Nipmuck, Pocumtuck, and Narragansett tribes following the rapid expansion of colonial territories. King Philip's War (1675-1676) was the last major effort by the Native Americans of this region to drive out the English settlers. Members of the Mohegan, Pequot, and Nauset tribes joined with the colonists for, as some called it, the United States' most devastating conflict. One in ten soldiers on both sides was killed. The war lasted fourteen months, ending on August 12, 1676, with the death of Chief Metacom.
In 1700, a six mile square tract was granted to the King Philip's War Veterans. It was from this act that the town of Voluntown or "Volunteer Town" received its name. "Volunteer Town" was incorporated as Voluntown in 1721.
Old cellar holes and miles of stone fence winding through the woods give evidence that the entire forest was once farmed or pastured. Abundant water encouraged the establishment of a mill industry as early as 1711. Nearly every brook has several old mill sites and dams. Homestead farming and small industry succumbed to advancing modern technology; eventually, the forest reclaimed its land.