It was Day 42 of the Zaca Fire. A tower of white smoke reached miles into the blue sky above the undulating ridges of Santa Barbara's backcountry.

Helicopters ferried firefighters across the saw-toothed terrain and bombed fiery ridges with water. Long plumes of red retardant trailed from the belly of a DC-10 air tanker. Bulldozers cut defensive lines through pygmy forests of chaparral.

A few miles south, in a camp city of tents and air-conditioned office trailers, commanders pored over computer projections of the fire's likely spread, trying to keep the Zaca bottled up in the wilderness and out of the neighborhoods of Santa Barbara and Montecito.

Platoons of private contractors serviced the bustling encampment, dishing out hundreds of hot meals at a time from a mobile kitchen, scrubbing 500 loads of laundry a day, even changing the linens in sleeping trailers.

On this single day, Aug. 14, fighting the Zaca cost more than $2.5 million. By the time the blaze was out nearly three months later, the bill had reached at least $140 million, making it one of the most expensive wildfire fights ever waged by the U.S. Forest Service.

A century after the government declared war on wildfire, fire is gaining the upper hand. From the canyons of California to the forests of the Rocky Mountains and the grasslands of Texas, fires are growing bigger, fiercer and costlier to put out. And there is no end in sight.

Across the country, flames have blackened an average of 7.24 million acres a year this decade. That's twice the average of the 1990s. Wildfires burned more than 9 million acres last year and are on pace to match that figure in 2008.

At 240,207 acres, the Zaca was the second-biggest wildland blaze in California's modern record. But nationally, it wasn't even the largest of 2007. A conflagration on the Idaho-Nevada border charred more than twice as much land.

In response, firefighting has assumed the scale and sophistication of military operations. Consider the forces massed against the Zaca that sweltering August afternoon: nearly 2,900 federal, state and local firefighters, 122 fire engines, 35 bulldozers and a small air force of 20 helicopters and half a dozen air tankers.

Private contractors are taking on a major role in the nation's wildfire battle, supplying much of the equipment, most of the camp services and even some firefighting crews.

Wildfire costs are busting the Forest Service budget. A decade ago, the agency spent $307 million on fire suppression. Last year, it spent $1.37 billion.

Fire is chewing through so much Forest Service money that Congress is considering a separate federal account to cover the cost of catastrophic blazes.

In California, state wildfire spending has shot up 150% in the last decade, to more than $1 billion a year.

"We've lost control," said Stephen J. Pyne, a professor of life sciences at Arizona State University and the nation's preeminent fire historian.

This "ecological insurgency," as Pyne calls it, has varied causes. Drought is parching vegetation. Rising temperatures associated with climate change are shrinking mountain snowpacks, giving fire seasons a jump-start by drying out forests earlier in the summer. The spread of invasive grasses that burn more readily than native plants is making parts of the West ever more flammable.

The government's long campaign to tame wildfire has, perversely, made the problem worse.

By stamping out most wildland blazes as quickly as possible, the Forest Service has stymied nature's housekeeping -- the frequent, well-behaved fires that once cleaned up the pine forests of the Sierra Nevada and the Southwest. Now, woodlands are tangled with thick growth and dead branches. When fires break out, they often explode.

Firefighters still manage to snuff out the vast majority of wildfires in their early days. But the 2% to 3% that break away are "more aggressive and more difficult to contain and bigger and badder every year," said Dave Bartlett, fire management officer for Sequoia and Kings Canyon National Parks.

Year after year, development relentlessly throws more homes into this combustible mix, escalating property losses and raising the political stakes.