A big-hearted act of preservation

The Cockpit Point Battery's positions still exist right where rebels dug them in a comic opera attempt to "blockade Washington."

Johnston's Army of the Potomac manned artillery pieces with infantry militia, took the occasional potshot at some passing steamer, and generally succeeded in irritating Washington Radicals. According to this story:
Richard and Barbara Tiplady bought 16 acres of woods along the Potomac River in Dumfries in 1987 because it reminded them of Flirtation Walk, a pedestrian path for cadets at West Point where they had gone on their first few dates.
They paid $30,000 for it. They discovered it held the battery's old positions.
After negotiations and assurances that the fort would be preserved, the Tipladys sold the historical land in September for about $1.2 million to Vienna-based developer KSI Services
Forty times the original price ... goodbye Flirtation Walk.
"When you develop in a community, you look for things you can do," said Edward S. Byrne, senior vice president at KSI, which is building Harbor Station -- a luxury hotel and conference center with a Jack Nicklaus-designed golf course -- at the site. "It's usually giving money for schools or transportation. When we looked around, people said, 'You know, there's this property with historical significance.' "
So there's going to be this Civil War artillery position preserved among the fairways and sandtraps.

I don't think preservationists have an answer to this; we even see Civil War Preservation Trust actively courting developers to buy and build on Civil War sites, setting aside some remnant for historical use.

It's coming. "Harbor Station - harboring all your Civil War history needs."