Manassas National Battlefield Park was designated a Federal area May 10, 1940. The 1,670.74 acres of federally owned land in the park comprise portions of the two battlefields.

One of the initial steps in the memorialization of these fields was taken in 1922 with the purchase of the Henry Farm, of approximately 128 acres, by the Manassas Battlefield Confederate Park, Inc., and the Sons of Confederate Veterans. On March 19, 1938, the Henry Farm was conveyed by deed to the United States Government as an “everlasting memorial to the soldiers of the Blue and Gray.” Significant additions to park holdings were made in 1949 with the acquisition of the historic Stone House and Dogan House properties.