A wetland restored to its Civil War-era condition was on public display yesterday at the Manassas Battlefield as National Park Service officials formally thanked the agency responsible for creating an authentic landscape on more than 100 acres.

In an unusual partnership, the Smithsonian Institution restored the area to make up for land it disturbed when building its National Air and Space Museum annex near Dulles International Airport. Otherwise, battlefield managers said, the Park Service might never have found the money to restore land at the park near Manassas that Congress had seized from a mall developer in the 1980s.

Park Service Director Fran P. Mainella said it would have been many years before the cash-strapped agency could have afforded to do the project itself.

"It's a great accomplishment that rightly makes each partner proud," Mainella said. She was joined by Smithsonian officials, volunteers in heavy wool Civil War uniforms and even a slithering water snake that appeared to be enjoying some of the new wetland.

With some financial help from Virginia, the Smithsonian has restored 115 acres to the way they were during the Second Battle of Manassas in August 1862. Workers rearranged 90,000 cubic yards of dirt and planted more than 50,000 native plants and grasses at a cost of more than $1.4 million.

They were charged not only with re-creating every hill and berm, but also with restoring nature's original plumbing on the site, making sure that places that were wet in 1862 will be wet in the future. The mud and the snake and other water-borne critters visible yesterday attested to their success.

The land, west of the original battlefield park between Interstate 66 and Route 29, was bulldozed during the 1980s by developer John T. "Til" Hazel, who was planning the William Center, a giant mall and subdivision.

Although the Hazel land was private and not part of the park, historians said it was integral to understanding the Second Battle of Manassas and included grounds where Confederate Gen. Robert E. Lee's headquarters had stood. Hazel's development plan led to a national outcry by preservationists, and images of backhoes and bulldozers ripping up a Civil War battlefield galvanized the public. In 1988, Congress bought Hazel's land and added it to the battlefield.

When the Smithsonian was planning the Steven F. Udvar-Hazy Center at Dulles, it needed to find a way to replace seven acres of an emerging boggy area that it would disturb for the new Air and Space Museum annex.

Lin Ezell, a top museum official, was driving one day and saw the brown sign for the Manassas Battlefield. She realized that restoring wetlands on another federal property in the same area -- instead of buying expensive private property for the project -- would be the cheapest and easiest solution. She got back to the office and called the park.

Robert K. Sutton, the superintendent of Manassas National Battlefield Park, was more than amenable.

"I said yes," Sutton recalled, even though "I didn't know exactly when or how."

"We couldn't build at Dulles without a wetlands [replacement] plan," Ezell said. "I called Bob, and the rest is history."

A huge help in the project were detailed topographical maps of the area during the Second Battle of Manassas. The maps were commissioned for the retrial of Union Gen. Fitz-John Porter, who was trying to clear his name after being court-martialed for cowardice during the battle. The maps helped prove that Porter did all he could during the battle, which was won by Confederate forces.

Mainella, who served as Florida's parks director before being named to head the Park Service in 2001, said forming partnerships like the one at Manassas is the only option for the Park Service as it struggles to keep up with maintenance and resource protection at the nation's 388 parks.

"We all need each other," Mainella said.

Sutton said he is still looking for partners to help finish the picnic area near the restored wetland and to help build a solar-powered restroom at the site.

Officials look over the new wetland in the 115-acre restored section of the battlefield, which now follows the topography shown in Civil War-era maps and includes more than 50,000 newly added native plants.National Park Service Director Fran P. Mainella calls the restoration "a great accomplishment."The restored section of the Manassas battlefield has become home to wetland wildlife again.