Park historian Dennis Frye said the latest acquisition from the trust will bring the park's total land holdings to nearly 3,500 acres.
Thursday's land transfer ceremony was held on a 56-acre tract, now part of the park on Bakerton Road north of U.S. 340. That tract was saved by the Civil War Trust in 1995.
The Civil War Trust, headquartered in Hagerstown, and the Association for the Preservation of Civil War Sites in Arlington, Va., merged in 1999 to form the Civil War Preservation Trust, the largest nonprofit battlefield preservation organization in the country, Koik said.
The trust has 55,000 members. Since 1987, it has saved more than 25,000 acres of Civil War battlefield lands.
Frye, in explaining the importance of the new acquisition to the park, said the land figured heavily in the Battle of Harpers Ferry on Sept. 15, 1862.
Confederate forces under Gen. Stonewall Jackson and his 15,000 troops launched their attack on the 14,000 Union troops holding the high ground on Bolivar Heights from ground included in the 176 acres. The Union troops were lined up on Bolivar Heights to defend Harpers Ferry, Frye said.
Jackson's men came down from the high ground they were holding beyond School House Ridge, marched across Bakerton Road and headed up the hill toward the Union forces and guns.
Jackson outfoxed the Union troops with a flanking attack and captured the entire garrison of more than 12,000 troops, the greatest number of American forces captured at one time until the Japanese captured Bataan in the Philippines in World War II, according to a National Park Service plaque.
"I guarantee you that this would not be the national park's backyard today, but a developer's dream," Frye said. "This is battlefield land. Men died here."
In all, about 300 soldiers lost their lives in the battle, Frye said.
Harpers Ferry National Historical Park, in anticipation of the land's donation, already has built restrooms and a visitors parking lot. Walking trails will be built and interpretive signs will be installed on the new property.