The fading scars of old wars can still be seen in the fields of France, the sands of North Africa and the jungles of Vietnam.

Now a foamy slick of crude oil despoiling the Persian Gulf has written a new page in the history of environmental warfare, a sad chronicle dating back at least to 146 B.C., when Roman soldiers sowed salt on the site of defeated Carthage.It didn't work. Carthage eventually came back to life. But at Verdun, France, where World War I artillery shells rained on dug-in soldiers for months, some patches are still dead.

"There's still an area there that's hardly recovered," said Russell Parkinson, staff historian at the U.S. Army's center for military history. "There's still bands there that are not usable."

In Vietnam, millions of gallons of herbicide were dumped on tropical forests in an effort to bring guerrillas out in the open.

"The Vietnamese lost over 5 million acres of forest and farmland," said Elizabeth Kemf, who recently published a book, "Month of Pure Light," about that country's efforts to reclaim land from wartime devastation.

"The people are still filling in some 25 million bomb craters. People everywhere can be seen planting trees," she said in a telephone interview from Geneva, Switzerland. But it might take 200 years to regrow the rain forest to its former glory, she said.

And Vietnamese authorities report high incidence of cancer, birth defects and miscarriages in the area where Agent Orange and other herbicides were employed.

The history of war also records cases of self-inflicted damage.

When the German army moved into the Netherlands in May 1940, the defenders breached the dikes that protected the fertile lowlands from the ocean's saltwater.

"The Dutch flooded the land to impede the advance of the Germans," Parkinson said. "The salt had to be leached out of the earth, which took 20 to 30 years."

For environmentalists alarmed at what the war with Iraq might bring, the huge oil slick in the Persian Gulf looks like just the beginning.

"Deserts are fragile ecosystems without much regenerative power," said Lester Brown, president of the Worldwatch Institute, a Washington think tank. "The tank tracks in Libya from the World War II battles with Rommel are still there."

Michael Renner, a Worldwatch researcher who has studied the military's impact on the environment, said some projections of worldwide ecological disaster from the gulf war may be overstated.

"It's much safer to assume that there could be a significant regional effect," he said. "If the Iraqis were to blow up a lot of oil wells at once, it could go on for weeks if not months."

The smoke and soot could disrupt growing seasons and harvests at least as far away as India, where a small imbalance in food supplies could have major effects, Renner said.

In addition, the tanks, jets, helicopters and warships use large quantities of fuel in their daily operations. Renner estimated that each aerial sortie - and there have been tens of thousands - uses as much fuel as an average American motorist would burn in three years.

In addition, military bases in the United States have been among the worst sources of hazardous wastes needing cleanup under the Superfund program.

"When you look at the large amounts of toxic substances being handled, you're going to see a lot of contamination of the Saudi desert," Renner said. "When the war is over, you're going to hear a lot about contamination, perhaps to ground-water."

In wars past and present, the threat of environmental destruction has never ranked high among policy-makers' concerns - not up against the direct risk to human life and the national interests that make war seem worth the cost.

"I can see why people don't pay a lot of attention to this now," Renner said. "But in years to come when the war is forgotten, there will still be environmental problems. This will be the lasting legacy."