Authorities levied a tax of $92.07 on the Lees' estate that year. Mary Lee, stuck in Richmond because of the fighting and her deteriorating health, dispatched her cousin Philip R. Fendall to pay the bill. But when Fendall presented himself before the commissioners in Alexandria, they said they would accept money only from Mary Lee herself. Declaring the property in default, they put it up for sale.
The auction took place on January 11, 1864, a day so cold that blocks of ice stopped boat traffic on the Potomac. The sole bid came from the federal government, which offered $26,800, well under the estate's assessed value of $34,100. According to the certificate of sale, Arlington's new owner intended to reserve the property "for Government use, for war, military, charitable and educational purposes."
However, after the war the US was forced to pay up for what it had "appropriated" by a property tax sale.
http://www.smithsonianmag.com/history/h ... 145147007/