Correction: An earlier version of this post incorrectly stated how much land was being transferred.

The Gaines’ Mill Battlefield, part of the Richmond National Battlefield Park, grew by 285 acres Thursday morning, when the Civil War Trust officially transferred a tract of land to the National Park Service. The addition expands the national park, which includes areas in Richmond and surrounding counties.

The move protects the site of the first major victory for the Army of Northern Virginia’s commander Gen. Robert E. Lee, on June 27, 1862. It was purchased in 2012 following a successful one-year campaign by the Civil War Trust to raise $3.2 million. Funding came from private donations as well as a matching grant from the state of Virginia. The integration of the land into the National Park Service was made possible through the 50-year-old Land and Water Conservation Fund.

Interior Secretary Sally Jewel was scheduled to preside at the ceremony. Also expected to speak were James Lighthizer, the trust’s president, and Virginia Natural Resources Secretary Molly Ward.

According to a media release, the transferred property, known as the McDougle Tract, “played a key role in the development of aeronautical observation in military intelligence. During the battle, both armies had observation balloons aloft — the first instance in American history —with the Union Intrepid launching from the vicinity of the McDougle Tract.”