Fort Belknap, located near Newcastle, Texas, was established in November 1851 by brevet Brigadier General William G. Belknap to protect the Texas frontier against raids by the Kiowa and Comanche. It was the northernmost fort in a line from the Rio Grande to the Red River. The fort functioned as a base of operations rather than as a fortified point, and it became the center of a substantial network of roads, including the Butterfield Overland Mail. The fort was designated a National Historic Landmark in 1960, in recognition of its key role in securing the Texas frontier in the 1850s and 1860s.