This summer Branson McRae, president of a Wadeville, N.C., combat boot maker, laid off 100 employees and hunkered down for the worst. The Cold War was over, military spending was down and the Defense Department "just practically stopped ordering boots," he said. Someone was going to go out of business, and "I certainly didn't want it to be me."

Then U.S. troops began massing in the Persian Gulf region, and that has changed everything.

In October, McRae won a Pentagon contract for 199,000 hot weather boots; he has rehired workers and expects his production lines will soon be running at "full blast." His $8 million deal is just a small part of the estimated $30 billion cost this fiscal year of Operation Desert Shield, but it is symbolic of the surging industrial support that lies behind the U.S. deployment.

A vast and growing network of food and clothing manufacturers, trucking companies and other specialized firms has been pushing out supplies at a breakneck pace. Firms large and small have added workers and are running night and weekend shifts to keep up with the Pentagon's increasing demands. Virtually every key decision, whether deploying additional troops or setting a Jan. 15 deadline for Iraq to withdraw its troops from Kuwait, has set off a logistics ripple effect across the United States.

"In normal times you have a lot of reviews and things. You skip that in this kind of emergency," said Tom Ray, a procurement analyst for the Defense Logistics Agency, which is carrying out the crash effort to acquire clothing, medical and food supplies, spare parts and other materiel.

Added Richard E. Donnelly, who recently served as acting deputy assistant secretary of defense for production: "National security comes in many flavors. It just isn't men and women, ships, aircraft and tanks; it's the ability of our industrial infrastructure to supply."

Apart from the sheer size and speed of the military buildup in the gulf, the desert environment in which it is taking place has put extraordinary demands on the supply system. "It's kind of like you packed to go on vacation in Alaska and you ended up in Hawaii," said Donna M. Heivilin, director of logistics issues for the General Accounting Office.

Clothing manufacturers have been ordered to switch from the traditional woodland green combat fatigue to a lighter, desert tan version. The steel plates that lined the soles of combat boots, designed as protection against sharp punji stakes in Vietnam, have been removed because they were unnecessary and got hot, officials said. Special care has been taken to provide food products capable of withstanding extreme desert heat.

Operation Desert Shield's effect is being felt in places such as Beloit, Wis., and Plainview, Minn., both locations of Geo. A. Hormel & Co. plants that are working overtime to fill a $44.6 million order for microwavable entrees of pot roast, lasagna and other food items.

The pace got so intense last month that Hormel told some commercial customers certain promised orders were being diverted to the Pentagon. Some, like Giant Food in Landover, did not object, but other firms -- including a large food chain -- were unsympathetic.

"Let's put it this way: it strained our relationship with some of our important accounts," said Eric Brown, a Hormel vice president.

In dozens of apparel factories in the rural South, uniforms are being produced and jobs have been created at a time when economic prospects seemed bleak.

In Mayaguez, Puerto Rico, a clothing and flak jacket manufacturer contacted the local unemployment office to help find 250 workers after receiving an $11.4 million Desert Shield contract.

In Brooklyn, N.Y., the Isratex line of chemical warfare protection suits suddenly has a new market. And inside the Bastrop, Tex., federal prison, 110 inmates are being paid approximately 88 cents an hour to rivet bullet-resistant helmets.

Perhaps the most critical supplier in the days immediately after the August decision to deploy U.S. troops to the gulf was an ancient clothing factory in a busy neighborhood in South Philadelphia. The only such factory owned by the Defense Department, the plant once outfitted soldiers in the Civil War. Now, 1,500 uniforms, 700 hats and 700 canteen covers are being churned out daily by 1,000 civilian employees.

One worker, Ella Abner, 68, started at the plant 48 years ago. She remembers operating a sewing machine during World War II, in which her brother fought. She bundled uniforms during the war in Vietnam, where her son served. Now she removes spots from new desert fatigues and writes to Emmett Abner, her 20-year-old grandson, a Marine in the gulf.

Elsewhere in the sprawling complex, which includes offices of the Defense Personnel Support Center, officials are cutting red tape to make the necessary deals to meet the Pentagon's urgent timetable. "Paperwork to follow" is the byword of the hour. Where once it took up to six months to consummate a military contract, huge deals now are arranged in just a few days.

For example, Wrangler, the jeans maker, had not done defense work since the days of the Vietnam War. On Oct. 2, it was contacted by the Defense Logistics Agency, and on Oct. 17, it had a sole-source, $17.2 million contract to produce 1 million pairs of battle fatigues. The first ones came off the line Tuesday.

The chief commercial beneficiaries of Desert Shield appear to be specialized companies -- the makers of uniforms, producers of boots, assemblers of food packages and manufacturers of everything from chigger repellant to sunglasses to nerve gas antidote.

Paradoxically, the huge contractors that provide the Pentagon with its most sophisticated and expensive systems have so far benefited less, experts said.

"The performance of the supply system of Desert Shield has nothing to do with the ability of the {defense} industry to react to a crisis," said James Blackwell, a senior fellow at Center for Strategic and International Studies, who studies defense industrial issues. "It has everything to do with the fact that people in the supply business were able to take things off the shelves and move them down to Saudi Arabia," thanks in large part to surpluses resulting from the Pentagon's huge acquisitions programs of the 1980s.

"I think the system's basically living off of what was already in the pipeline," said Norman R. Augustine, chairman and CEO of Martin Marietta Corp., and a former undersecretary of the Army. "There's been very little impact on the industry as a whole, and certainly that's true of our company."

Augustine said several of his firm's systems are part of the Desert Shield operation -- such as Hellfire laser-guided missiles for Army attack helicopters and the LANTIRN nighttime navigational system for Air Force fighters -- but the production of only one set of items -- portions of the Patriot missile made for Raytheon -- has been accelerated.

Although many defense experts said Operation Desert Shield offers no promise of reversing planned reductions in future defense budgets, some bigger firms may still benefit from the proposed $20 billion Saudi arms package and other arms deals involving Middle Eastern countries.

Meanwhile, hundreds of firms around the United States continue to manage the day-to-day problems of keeping alive the supply lines to the gulf.

In Vineland, N.J., National Freight, on call seven days a week for the Defense Logistics Agency, is one of several firms with contracts to haul supplies from manufacturers to military depots in places such as Memphis and Richmond. The burst in business has enlivened an otherwise slow holiday season. "I don't want to see us go to war," said Jeff Brown, vice president for sales and marketing, "but it certainly fit in. . . . The government came at a real nice time."

In Lincoln, Neb., Calvin Fisher, owner of Fisher Foods and an inventor of "spray-dried," just-add-water scrambled eggs, said a new $14 million Desert Shield contract for his "Ready Egg" is triple his normal annual military sales, and he suspects the troops will soon need more of his product.

"For cripes sake," he said of the soldiers stationed in the desert, "they've got them cooped up, they can't go anyplace and they're eating like crazy."

The three firms that produce MREs -- the dehydrated Meals Ready-to-Eat that constitute a main source of nourishment for U.S. troops in the desert -- were expecting cutbacks in Defense Department purchases of nearly 30 percent this year. But sales soared after the gulf deployment began, from 2 1/4 million cases annually to 2.4 million cases per month, said Terry Bevels, the industry's Washington representative. "We can barely keep up with the demand."

Wrangler's contract with the Pentagon may pay off in more ways than one. After it was announced, the firm was deluged with calls, said Bill Koronis, a company official. An upscale mail-order house wanted a line of camouflage trousers. A national retailer asked for camouflage childrens' shorts. Several Saudis called from Riyadh, Saudi Arabia, requesting a private deal with the firm.

The news is also good for Wadeville, N.C., where McRae's big layoff had a severe impact in the community of 1,000. It could have all been avoided, said McRae, who said he warned defense logistics officials last year that their decision to stop purchasing combat boots was unwise.

"We had a meeting with them. We told them, 'Look, you've got to keep us alive. You don't know when a war will break out. . . . We've always had a war sooner or later.' "