Pulitzer Prize-winning historian James McPherson has called it a "clash of titans," a battle over Princeton land linking two giants of American history: George Washington, father of the country, and Albert Einstein, father of modern physics.

On one side are scholars and preservationists who see the 21-acre tract owned by the Institute for Advanced Study as hallowed ground where Washington led American troops to victory over the British in 1777.

On the other side is the institute, where Einstein was a faculty member and where scientists see the land, next to Princeton Battlefield State Park, as the site of much-needed faculty housing.

McPherson and fellow Pulitzer Prize-winning historian David Hackett Fischer have proposed a compromise that would permanently preserve about 14 acres and allow 15 housing units, screened by trees, to be built on seven acres.

The plan, accepted by the institute, calls for archaeological work to recover artifacts, a 200-foot buffer zone next to the park, interpretive markers to help visitors understand the battle, and removal of trees and brush not present in 1777.

But opponents have rejected the proposal, and the two sides are locked in a battle over the future of the tract with its connections to the past.

Final arguments will be made before the Princeton Regional Planning Board at 7:30 p.m. Thursday. The hearing is the fourth and may be immediately followed by a decision.

"It's a really thorny issue," said Cate Litvack, former director of the Crossroads of the American Revolution National Heritage Area and a former mayor of Princeton Township. "We hope the building doesn't happen because this was a pivotal battle."

"We're looking for common ground," she said.

The Princeton battle "was a must-win for Washington, and it's a must-win for us," said Jerry Hurwitz, president of the Princeton Battlefield Society, a nonprofit organization that has opposed the housing proposal since it went before the planning board in 2003. "There are few preserved battlefields of the American Revolution. That's why this is a level-one priority."

The Princeton battle on Jan. 3, 1777, marked Washington's first victory over British regulars. His ragtag army defeated Hessian mercenaries at Trenton on Dec. 26, 1776, and was swept aside by Redcoats at the Second Battle of Trenton on Jan. 2, 1777.

"If it wasn't for Washington, Einstein wouldn't have had a country to come to," said Hurwitz, a lawyer. "What would people think if we put a housing development where Flight 93 came down on 9/11?"

"We're not trying to save every blade of grass on the battlefield, but this was the site where the climax of the battle was fought," he said. "It's unthinkable" to place housing there.

The building project is long overdue, say officials at the Institute for Advanced Study, which dismisses opponents' claims that important fighting took place on the site. Archaeological work there uncovered artifacts consistent with troop movements, not a major engagement, they say.

"We don't see any real conflict," institute director Peter Goddard said. "You should create a place to memorialize [the battle]. What you can't do is freeze history."

Troops moved across wide areas, including what is now Princeton University and other built-up areas nearby.

"The nature of history is that much of it you don't know for sure," Goddard said.

The institute has been "extremely sensitive to the battlefield," spokeswoman Christine Ferrara said. "The park would not exist if not for the institute. It conveyed 60 percent of the parkland to the state" in 1973.

The sale of those 32 acres was made based on a state commitment that the institute's land east of the battlefield park's boundary could be used as the future site of housing, officials said.

The additional housing would help faculty members spend more time on the campus and encourage collaboration between them and visiting scholars on a host of academic pursuits.

Einstein, a faculty member from 1933 until his death in 1955, lived less than a mile away and sometimes walked to the institute. He was often seen strolling the grounds with other scholars, discussing physics.

Einstein "was active in giving lectures and mentoring other scientists," Ferrara said. "This is not like a university where the faculty teaches and gives exams. This is a place where scholars have the freedom to pursue intellectual curiosity, and that can result in wonderful things."

The institute has 28 permanent faculty, 14 emeritus faculty, and 190 visiting scholars who live in on- and off-campus houses and apartments. The new project calls for the construction of eight townhouses and seven single-family houses.

But some historians believe the proposed houses, even screened by trees, would disrupt the integrity of the battlefield. More than 50 military artifacts - including impacted musket balls and cannon grapeshot - have been discovered there.

McPherson and others tried to resolve the dispute with the compromise proposed in December.

"If all works out, maybe there will be interpretive markers and a walking path," said McPherson, best known as a Civil War historian and author of Battle Cry of Freedom. "This [compromise] would maximize access to the most relevant land and the institute would build on the remainder.

"If I had to predict, I would say the planning board is likely to approve the idea," said McPherson, who worked on the compromise with Fischer, who won a 2005 Pulitzer Prize for his book Washington's Crossing. "I think the institute, with goodwill, intends to carry out the terms" of the compromise.

But Hurwitz and other opponents say they'll fight on if the board's decision goes against them, even though just how much fighting took place on the institute's proposed housing site remains in dispute.

 "This is where you had the last organized British resistance," said Richard Patterson, executive director of the Old Barracks Museum in Trenton. "It was their last stand, like Custer's last stand.

"If this was Gettysburg, this would be the copse of trees that Pickett's charge was aiming for," he said. "That one piece of ground is very, very critical."

Contact staff writer Edward Colimore at 856-779-3833 or ecolimore@phillynews.com.