Nature joined forces with a high-tech human army here today as rain and cool weather helped firefighters control most of the major blazes that have scorched a quarter-million acres of Montana this week.

Although public officials were reluctant to declare victory, they said intermittent rains all day today had stopped most fires from spreading and given crews time to build fire lines that could contain the blazes.

Of the 13 major range and forest fires burning at dawn today, all but one -- the 12,000-acre Houghton Creek fire in the state's northwest corner -- apparently had stopped growing by nightfall.

The 28,000-acre North Hill fire, which earlier had threatened subdivisions north of Helena, "is only smoldering now," a Forest Service spokesman said. The Hawk Creek fire, which burned 140,000 acres near Billings, was nearing containment.

A 140,000-acre fire centered at the Washington Monument would extend five miles beyond the Capital Beltway.

Today's dramatic progress also was the result of round-the-clock efforts by a 5,000-member firefighting army equipped with reconnaissance planes and chemical-dumping bombers, paratroopers and foot soldiers.

The scene this morning on the perimeter of the North Hill fire resembled Vietnam as a battalion of men (and a few women) in green fatigues jumped out of jeeps and moved into the smoking forest while field commanders conversed by walkie-talkie with strategists hovering in helicopters above the treetops.

When a prairie or forest fire is larger than a few hundred acres (about the size of the Smithsonian Mall in Washington) it is normally too big for a "direct" attack -- that is, efforts to put it out with water or chemicals.

Instead, fires of the size found in Montana this week must be attacked at the edges. First firefighters try to build a "fire line" -- a road or ditch containing no flammable material -- around the blaze.

Once a blaze is thus "contained," fire crews work toward "control" -- developing a broader, more secure fire line that the blaze cannot cross even in high winds.

Once control is achieved, the fire will consume everything in its path and start to burn out. Firefighters try to hasten this by tracking down small blazes and dousing them with water or soil.

One difficulty in establishing an impassable fire line around a blaze is finding the perimeter. Even if weather conditions permit reconnaissance flights over the burning area, billowing smoke can obscure the path and extent of the flames.

Accordingly, a firefighting day here begins with overflights shortly after midnight by planes equipped with infrared scanners. They produce videotapes showing the hottest parts of the range or forest -- and thus where the worst fires are.

With this information, and with meteorological forecasts of wind, rain, and temperature, the "fire boss" dispatches his troops by helicopter, jeep or truck.

The ideal tool for building a burn-proof fire line is a bulldozer, which can plow a four-foot-wide swath in a single pass.

In the rugged, narrow hills and canyons of western Montana, though, bulldozers cannot always get where they are needed. Accordingly, the brunt of the work falls on crews of men and women each armed with a shovel or "Pulaski," a long-handled tool with an ax blade on one end and a hoe on the other.

When wind conditions are right, crews can literally fight fire with fire by igniting a "backfire" that will burn from the perimeter toward the heart of the blaze.

The foot soldiers of the fire wars in Montana this week have been mostly Forest Service workers from western states. Some National Guard troops were activated. In addition, inmates from the state prison farm were trucked out to fire duty. For safety reasons they could not be shackled.

"Let's just say they are under extremely close supervision," said Dorothy Terry, a Forest Service worker.

While the foot soldiers are securing the perimeter, the fire boss also can call in air strikes. Large planes, many of them converted military bombers, sweep in as low as 150 feet above the forest and drop thousands of gallons of fire retardant in the path of the fire.

The Green Berets of the firefighting establishment are the "smoke jumpers," Forest Service paratroopers who jump into a burning forest with chain saws and other tools.

Once on the ground, the smoke jumpers try to cut out a clearing so that helicopters can ferry in more men and equipment.

The smoke jumpers are equipped as well with specially programmed calculators and a "hauling chart." These tools tell them when the fire's progress is such that they should "haul" out of the forest as quickly as possible.

For all this high-tech apparatus, however, the most powerful weapon in controlling a wildfire is still the weather. It was a combination of hot, dry weather and gusty winds that whipped small fires in Montana last weekend into major ones.

The week's first rain started falling here in the northwest part of the state Thursday night, and by today wet weather had spread through most of the western half of Montana.

Radio weathermen throughout the state this morning made the unusual announcement that the forecast for Labor Day weekend was "just what we wanted: cool temperatures, gray skies and a good chance of rain."

Forest Service officials overseeing the fire fight here expressed restrained optimism about the turn in the weather.

"Thank God we finally got some rain to give us time to make some strategy," said Sonny Stiger, the fire boss on two smaller fires near Helena. "But if this gives way to that hot, windy stuff again, these fires could start spreading all over again."