Arnold & Porter senior counsel Robert Rosenbaum pulls a bundle of rolled-up maps out of a cardboard cylinder stowed in his Washington, D.C., office.

He spreads the maps across his desk. They diagram the Battle of the Wilderness, where, in May 1864, more than 160,000 Union and Confederate troops descended on a patch of forested land west of Fredericksburg, Virginia. The Wilderness marked the first time Robert E. Lee and Ulysses S. Grant led troops in battle against one another. Fighting was so fierce that brush on the forest floor caught fire, burning some wounded men alive. Nearly 30,000 men were killed or wounded.

Rosenbaum, 68, points to blue arrows indicating an offensive push by a Union company, black lines showing the entrenchments dug by each side, and red arrows indicating a flanking maneuver by the Confederates.

As Rosenbaum’s hand passes over the color-coded battle lines, it hovers above an intersection that was recently the site of a proposed 51-acre commercial development. The area was to include a Wal-Mart Supercenter, two other commercial buildings, and large swaths of parking—adjacent to the entryway to the national park where the Battle of the Wilderness took place. But thanks to the pro bono efforts of Rosenbaum and his A&P colleagues on behalf of a group of six local residents and a local nonprofit, the site will be preserved. In January, on the second day of what was to be two weeks of trial challenging the approval of the development in state court in Orange, Virginia, Wal-Mart Stores, Inc.—represented by McGuireWoods—announced that it was dropping plans to build on the site, opting instead to preserve it.

Rosenbaum’s success in the Wilderness Battlefield fight is the latest in a string of impressive pro bono results. Since the middle of the past decade, Rosenbaum has been on the front lines of cases that have limited the number of snowmobiles in Yellowstone National Park, dissuaded developers from building a convention center in the heart of Valley Forge National Historical Park, and shaped federal policies governing the use of off-road vehicles in the national park system. “The matters that I’ve been involved in are matters that test the statements that are made about our national parks: that these are national treasures, that these are places that need to be saved for future generations,” Rosenbaum says. “Do we really mean what we say?”

Rosenbaum’s love of the national parks dates back to a ten-day car trip he and his family took when he was 10. He, his parents, his three siblings, and his grandmother packed into the family Buick for a trek from their Dallas home to Carlsbad Caverns, Mesa Verde, and Rocky Mountain National Parks as they crisscrossed the American West. After college at The University of Pennsylvania and law school at Columbia, Rosenbaum moved to Washington, D.C., to take a job at Arnold & Porter in 1968 and start a family of his own. Over the years he and his wife have taken their own two sons hiking in the nearby Shenandoah National Park and made trips to Yosemite, Kings Canyon, and Rocky Mountain National Parks. Asked what draws him to the parks, Rosenbaum says, “First of all it’s the solitude. You’re away from civilization. And second it’s quiet. . . . There are these natural things that are bigger and older than you are,” he says. He says the feeling one gets in the parks puts daily concerns in perspective.

Rosenbaum’s conservation work began when he was still a partner in the early 2000s. He had mentioned to New York environmental partner Michael Gerrard (now a senior counsel) that he was interested in working on conservation issues. Gerrard passed along a request from an ABA e-mail list from a potential client who was working on an effort to keep personal watercraft out of the national parks, but A&P was conflicted out of the case.

In 2004 the client came back to Rosenbaum with a different matter involving the use of off-road vehicles in the parks. After initially trying to work with federal officials on the issue, Rosenbaum filed suit in November 2005 against the National Park Service and the U.S. Department of the Interior in federal district court in Washington, D.C., on behalf of a group of nonprofits, including the National Parks Conservation Association (NPCA). The suit alleged that federal agencies failed to protect the parks against the damages caused by off-road vehicles. The litigation settled in May 2008 with the Park Service agreeing to run a pilot education and deterrence program at ten national parks and pledging to develop environmental impact statements at other parks across the country.

The NPCA, which has a mission to protect the parks, became the chief client driving many of Rosenbaum’s matters. In 2006 Rosenbaum helped lead the organization’s challenge to the Bush administration’s proposed rewrite of the park service’s management policies that could have opened the parks up to more personal watercraft, off-road vehicle, and snowmobile use. In 2007 he represented the NPCA and local residents near Valley Forge in challenging a local zoning board’s decision to allow commercial development on private land within Valley Forge National Historical Park. (During the course of that litigation, the developer abandoned plans to build on the Valley Forge land and swapped the land for unused Park Service property in Philadelphia.) Rosenbaum also joined the NPCA’s ongoing efforts to curb the use of snowmobiles in Yellowstone National Park. In September 2008 Rosenbaum and the NPCA won a ruling from Washington, D.C., federal district court judge Emmet Sullivan declaring that the Bush administration’s decision to increase snowmobile use in Yellowstone violated the Park Service’s mandate to protect the clean air, wildlife, and natural quiet of the parks.

Rosenbaum was a natural pick for field general when a group of local residents and a consortium of preservation organizations decided to mount a legal challenge to the commercial development near the Wilderness site in the summer of 2009. In August 2009 the local board of supervisors of Orange County, Virginia, approved a special permit to allow construction of the Wal-Mart Supercenter and other commercial buildings on the site at the intersection adjacent to the entrance of the Fredericksburg and Spotsylvania National Military Park. Once the permit was approved—which happened less than a month after Rosenbaum was brought in on the matter—the plaintiffs had a 30-day deadline to challenge the permit.

On September 23, 2009, the National Trust for Historic Preservation, the Friends of the Wilderness Battlefield, and a group of six local residents filed suit against the local board of supervisors in Orange, Virginia, state court. (The NPCA was dropped from the complaint because of a standing issue.)

The plaintiffs alleged that the local government had not followed its own comprehensive plan to promote economic development while preserving historic sites in the county, that local officials had violated Virginia state open-meetings laws in the way they handled the approval process, and that defendants were wrong to say that the proposed site did not have historic significance. The plaintiffs had retained the expert testimony of Pulitzer Prize–winning historian and Princeton professor James McPherson, who was prepared to testify that the site had been a “nerve center” of the Union army during the fighting. “This site is important for understanding the Battle of the Wilderness because of its centrality during the entire battle for Union troop movements on the roads through that intersection, artillery emplacements, infantry deployments, communications, and care of the wounded,” McPherson wrote in his expert testimony filed with the court in October 2010.

As the January 2011 trial date approached, Rosenbaum led a core team of about eight A&P lawyers as they helped the plaintiffs fulfill discovery requests and prepare witnesses for trial. Members of the Friends of the Wilderness Battlefield, a local nonprofit plaintiff with no paid staff, brought their computers into Arnold & Porter’s D.C. offices so that the firm’s technical staff could extract files to fulfill their discovery obligations. “It was a momentous task for us,” says Friends president Zann Nelson, of Culpeper, Virginia. “Bob helped us through all the technical points that we­—not being in the legal field—needed help with. Some of us have never been involved in litigation before,” she says. In total, 18 A&P lawyers put in 3,837 hours from August 2009 to January 2011. Rosenbaum alone put in nearly 1,500 hours. “Bob brought class A litigation skills and the resources of a national firm to a case that would normally get one real estate lawyer at best,” says Christopher Miller, a former Beveridge & Diamond associate who is now the president of the Piedmont Environmental Council, one of the nonprofit groups in the coalition engaged in the Wilderness Battlefield campaign.

On January 26 the work paid off. On the second day of what was expected to be two weeks of trial, Wal-Mart announced that it was withdrawing its request for the permit. Instead the company would buy the land, preserve it, and look for another site in Orange County.

Although the plaintiffs welcomed the news that the site would be preserved, the Wal-Mart announcement was met with mixed emotions from some the plaintiffs. “A lot of us were relieved that we wouldn’t have to testify,” says the Friends group’s Nelson. “But there was a large part of us that would have liked to have had our day in court with Bob Rosenbaum.” Rosenbaum puts it like this: “We were loaded for bear.” Beyond the disappointment of doing all the work associated with trial preparation without getting the payoff of going to trial, Rosenbaum says the courtroom battle could have been a “poster case” to shed light on the amount of power that local zoning officials hold over sites of national significance. Rosenbaum says he understands why local politicians would side with developers promising jobs to a region in desperate need of them. But some sites, he argues, should be left untouched for their value to the country’s heritage. “You can’t understand this country without learning about the Civil War. It’s just fundamental to who we are,” he says.

Bill Wertz, a spokesman for Wal-Mart, says there is no single reason for the company’s decision to abandon the original site, but said that the prospect of a lengthy litigation was a factor. “It’s not something that we relish, having to spend time in disputes and slowing down the process of getting a store built,” he says. Sharon Pandak, the county attorney for Orange County, says that litigation is not a productive approach to balance preservation with other land use and economic development issues. “There has been a lot of emotionalism that the plaintiffs have attached to their case that really has obscured the fact that the land had no significance to the battle,” she says. Wal-Mart ultimately reimbursed the county for its legal and administrative costs.

After the company backed out of the litigation, Jonathan Jarvis, the director of the National Park Service—which had not been party to the litigation—praised both Wal-Mart and the plaintiffs. In a statement, Jarvis said the company “crafted a solution where battlefield resources and the visitor experience will be protected while still providing for the commercial needs of Orange County. . . . Those involved in the suit and their partners have done a service for which we should all be grateful.”

In May the company drew praise from the preservation community when it proposed a similar development on land zoned commercial about three miles west of the Wilderness site.

Rosenbaum, too, is moving on from the Wilderness Battle. The maps of the battle site on Rosenbaum’s desk rest atop a map of Florida’s Big Cypress National Preserve, which sits due north of Everglades National Park. Last fall, the Park Service released a comprehensive plan for Big Cypress calling for an additional 130-plus miles of off-road vehicle trails in a newly acquired portion of the preserve, which is a prime habitat of the endangered Florida panther. Rosenbaum has been reading the plan closely.