Marc E. Bettius, a flamboyant Northern Virginia lawyer, dubbed it "The War of the Titans." Early this week, Fairfax Circuit Judge Johanna L. Fitzpatrick is expected to announce which of the Titans won.

The spoils: the rural southwestern quarter of Fairfax County with its last large section of undeveloped land; tens of millions of dollars in profits to be made from developing the land, and governmental power.

The war pitted the county government against some of the region's most expensive and influential development lawyers, including Bettius. It was fought mostly in Courtroom 4H of the Fairfax County Judicial Center, with occasional muttered skirmishes between the opposing lawyers when they found themselves on the same courthouse elevator.

The outcome, most persons connected with the case agree, will in large measure determine the kind of place Fairfax County will be well into the 21st century, the kind of roads, housing and taxes it will have, and the texture of its land and rhythm of its life.

"This case is all about a county's ability to control its own destiny," said Fairfax Supervisor Audrey Moore (D-Annandale), one of the most vigorous supporters of the county's action, and one of the few elected officials to attend the land-use trial nearly every day.

"The threat of development in the Occoquan [watershed] is far more imagined than real," Bettius said just before the trial opened.

"The War of the Titans" is a battle over land, a piece of land as big as the District of Columbia and as beautiful and unspoiled as any to be found within a 30-minute drive of downtown Washington.

The county government says it is trying to preserve that land, which comprises nearly a quarter of the county, to limit development on it to one home on every five acres.

Developers and landowners in the region want their previous development rights -- to build one home on each acre -- restored by the court, arguing among other things that the county board did not have the authority to limit development in the Occoquan watershed the way it did. They say the more restrictive zoning deprives them of their property rights and argue that the county has built its entire case on specious data.

"Using those same methods, I could prove to you that John F. Kennedy is alive in Dallas in 1984," Bettius told Fitzpatrick.

The trial -- one of the longest, most expensive and most bitter in Virginia -- ended Aug. 17, after 48 days of testimony from 32 witnesses spread over four months and more than 10,000 pages of testimony.

About the only thing on which the combatants agree is the importance of the case. It is important not just to a county board whose authority has been challenged, not just to developers with potential tens of millions of dollars at stake, but to the every resident of Fairfax.

"This is not a question of being concerned about what happens to your neighbor," said James E. Starrs, a professor of law at George Washington University and a 21-year resident of Fairfax, who has followed the case. "This is a question of being concerned about what happens to you. This will have a direct and immediate impact on just about everybody in Fairfax County."

More than that, the case has all the hallmarks of a precedent-setting land-use decision in Virginia. The outcome will determine how much authority local governments across the state have to control development and whether the state's courts are willing to end the prerogatives they traditionally have accorded landowners.

Whatever Fitzpatrick's decision, the case is almost certain to be appealed to the Virginia Supreme Court.

The land in dispute is referred to as the Occoquan area of the county because it makes up a large slice of the basin that drains into the Occoquan Reservoir and the Occoquan River.

Nearly 600,000 residents of Northern Virginia draw their drinking water from the reservoir. In July 1982, when the Fairfax County Board of Supervisors changed the zoning on the land, it said the action was necessary not only to protect the character of the land, but also to preserve the water supply from pollution.

The more restrictive zoning was challenged by more than 40 landowners -- large and small -- from the area.

The trial, conducted by Fitzpatrick without a jury, involved three landowner lawsuits, with the expectation that the outcome of the other 37 would become much clearer after the court had decided the major issues presented in the three cases.

The county and those who support it have argued not only that the county had the authority to limit development, but also that it had a moral obligation to do so in order to preserve the last unspoiled land in the county for future generations, and to safeguard an irreplaceable drinking water supply.

"Basically, the case is a question about the ability of local government to control environmental pollution and prevent environmental pollution through the use of the local zoning power," said David Bailey, director of the Virginia office of the Environmental Defense Fund. The fund filed a "friend of the court" brief in support of the county's action.

"What we have is Fairfax County, on its own initiative, taking affirmative action for the purpose of doing what it considers to be a benefit to the entire community," said law professor Starrs.

"They are trying to preserve the water supply. They are not just talking the good fight . . . but literally taking the bull by the horns, to do something concrete and affirmative," Starrs continued.

If the county loses its fight, Starrs and others believe, other local governments will be unlikely even to try to take the same sort of action, let alone spend the estimated $1.5 million to defend themselves in court.

"I'm not sure Fairfax County will ever try again, and I don't think any other county will ever try either," said Moore. If the county loses, she said, "people just better forget planning."

Moreover, those familiar with the county's case say a court loss could bring urbanization of the last bucolic section of the county and higher county taxes to build schools and roads into a new area of development at a time when such improvements are inadequate in the developed areas of the county, plus a dangerously polluted water supply a decade from now that could require millions of dollars to keep potable.

The lawyers for those who have challenged the county took issue in court with just about every contention. The county, they argued, did not have the authority to change the zoning. And in any case, the sort of development originally permitted would not endanger the water supply.

"This was a reaction to a theoretical problem," Bettius told the court.

What the county government was doing in effect, the attorneys argued, was creating an enclave of five-acre estates for the very rich out of what could have been an area of one-acre, single-family homes for the middle class in a county where single-family homes are increasingly expensive.

By shutting off the supply of new, affordable housing, opponents contend, the county discourages new industry from locating in the county and unnecessarily narrows the tax base.

Moreover, attorneys argued in court, the county's action deprived the Occoquan landowners of their property rights, unconstitutionally reducing the value of their land by tens of millions of dollars. If the county prevails in the suit, opponents warn, landowners around the state will not be protected from having the value of their land suddenly reduced.

The legal and scientific issues in the case are esoteric and complicated. Frequently, the courtroom resembled a university classroom more than a trial as both sides presented highly technical, scientific evidence about pollution and water quality management.

Fitzpatrick, who had been on the circuit court bench only a year when the case began, has been mulling and writing her decision for four months. It is expected today or tomorrow.

And although Fitzpatrick handed one major pretrial victory to each side, even the county's supporters are not optimistic that the county will prevail in Virginia, a state with a long history of court decisions sympathetic to landowners.

"Virginia has a long and very deplorable history . . . of upholding the rights of landowners," said Starrs. "Fairfax County and other counties are usually born losers when they try to do anything of a concrete nature to benefit the community."