Arlington National Cemetery is a sprawling 624 acres of prime real estate, directly across the Potomac River from Washington D.C. When the Civil War broke out in 1861, the hills overlooking the Capitol and the White House were a perfect spot for artillery. And Arlington, right on the cusp of the Union’s capital, was part of Virginia, which was about to secede from the Union.

It also happened to be the home of Col. Robert E. Lee, one of the most respected officers in the United States Army. He’d served with distinction in Mexico and put down John Brown’s raid on the U.S. arsenal at Harper’s Ferry in 1859. Lee was offered command of all Union troops at the outset of the war. Torn between his oath as an officer of the U.S. Army and his state voting to go to the Confederacy, Lee chose the latter, resigning his commission and becoming a brigadier general in the Confederate Army.

That the U.S. Army would seize Lee Mansion was a given, as it was needed to protect Washington D.C. and the seat of the United States government, but what happened in 1864 was unexpected. With the dead from the Civil War rapidly filling Washington’s existing cemeteries, U.S. Secretary of War Edwin Stanton signed the order to allow Quartermaster General Meigs to begin to bury the Union’s dead right outside of Lee Mansion, forever making it inhospitable for the family to inhabit it again.

It was designed and carried out to admonish and humiliate Lee for turning down his appointment and resigning his commission.