United States v. Lee (1882)
With local cemeteries in Alexandria County and Alexandria filling rapidly with war dead, Quartermaster General of the United States Army Montgomery C. Meigs proposed using of the Arlington estate as a cemetery. The first burial there was made on May 13, 1864. United States Secretary of War Edwin M. Stanton approved the establishment of a military cemetery on June 15, 1864, creating Arlington National Cemetery. By the end of the war in April 1865, more than 16,000 people had been buried at Arlington. In September 1866, a memorial and a burial vault (containing the remains of 2,111 U.S. and Confederate soldiers who died at the First Battle of Bull Run, Second Battle of Bull Run, and along the Rappahannock River) were buried in Lee's former wildflower garden on the mansion's east side beneath the Civil War Unknowns Monument, a memorial to honor unknown soldiers who had died during the American Civil War.
Navy Annex
A 1998 Congressional proposal to expand Arlington National Cemetery onto land that the Navy Annex and Fort Myer then occupied led to concerns that Arlington County officials had not been properly consulted, leading to the withdrawal of the proposal. However, the National Defense Authorization Act for Fiscal Year 2000 (Public Law 106-65), which was enacted into law during October 1999, subsequently required the Secretary of Defense to transfer to the Secretary of the Army administrative jurisdiction of the Navy Annex property. The Act required the Secretary of Defense to demolish the Annex's buildings and prepare the property for use as part of the Cemetery, while requiring the Secretary of the Army to incorporate the Annex property into the Cemetery.