Before anyone knew it, they had blossomed into world-class airlines, operating hundreds of jets on routes that straddle the United States and the globe. But what's this? They did it without offering in-flight movies or complimentary cocktails. And with schedules that most often have their planes flying in the dead of night.

Federal Express Corp., United Parcel Service and DHL Worldwide Express carry not people but things, and get them there overnight. With contrasting strategies and corporate cultures, each is struggling to set the pace in the fast-growing air express business, which sprang out of nowhere in the 1980s. Today their field of competition is not the country but the world at large.

United Parcel Service (UPS) and Federal Express (Fed Ex) dominate the U.S. domestic market and are now snapping up companies in Asia and Europe in an all-out effort to build overseas networks. DHL, leader in the foreign side of the business, is bolstering its defenses abroad through a new alliance with Lufthansa and Japan Air Lines and working to expand in the U.S. domestic market.

Competition has forced all three to come up fast with new services, and has driven returns down and debt up. "We could be more profitable in the short term," said Thomas R. Oliver, Fed Ex's senior vice president for international affairs. "But we really would lose the vitality of the company."

Check the holds of the planes that fly the darkened skies here and abroad and you might find parts for a broken-down BMW or factory robot, artists' sketches for an upcoming ad campaign, legal briefs, computer components, shipping documents or perfume samples. The occasional caged animal flies too, a rhinoceros bound for a new zoo, perhaps. About all these various cargoes have in common is that their owners want them to "be there" the next day.

After landing at floodlit hub airports, the jets disgorge their cargo and touch off a grand spectacle of organized chaos. While the customers sleep, thousands of part-time workers, many of them college students, rush to sort mountains of packages and envelopes and put them aboard other planes that will be in the air before the sun rises. "From 12:30 to 2:15 {a.m.} it's hectic, real hectic," said sorter Cleveland Brown, as he paused amid the din and conveyor belts of Fed Ex's main hub at the Memphis airport. "Stuff is coming constantly. We just keep going."

Not so long ago, Americans with something small to send used the local post office or the ubiquitous vans of UPS. Delivery generally took days, if not longer. People who tried air freight found it not always much faster. Shipments could sit for days on pallets in airport warehouses, waiting for customs clearance or the truck ride to the final destination. Agents had to be dealt with, long forms filled out.

Memphis-based Fed Ex, launched in 1973, changed all that, building next-day delivery into a mass industry. Customers loved it. Suddenly, anything less than overnight seemed hopelessly slow to many shippers. With Fed Ex growing by leaps and bounds, UPS was forced to offer a similar service, as were the U.S. Postal Service and a bevy of other, smaller air carriers such as Airborne and CF Airfreight.

Overnight mail drove the business at first. But in the late '80s the proliferation of facsimile machines took a bite out of that business. Yet express companies have found that there are still plenty of things fax machines can't handle (from the 100-page legal brief to the rhino) and vigorous expansion continued -- Moody's Investors Service last year estimated the overnight air business was expanding at about 20 percent a year.

Overnight service both grew from and drove the general acceleration of economic activity that occurred the world over in the 1980s. It fit neatly into the "just in time" philosophy of management that began in Japan and spread around the globe. Don't waste money stockpiling supplies of an item at a factory or store. Instead, arrange so that each part arrives just as it's needed. That means lots of little shipments rather than one big one, with a premium placed on delivery-date reliability.

As transoceanic trade mushroomed, American companies went global, giving domestic leaders Fed Ex and Greenwich, Conn.-based UPS a choice to go along or lose business. "More and more, companies are sending things internationally as well as domestically," noted David Guthrie, first vice president for research for Morgan Keegan & Co., a Memphis stock brokerage. "Those shippers want to deal with one company for both."

Express companies at first rented space in the bellies of passenger jets (and in many cases still do). But then in the late '70s deregulation made it possible for just about anyone to own an airline. In the '80s many companies jumped to assemble their own, building fleets that rival in size those of major passenger carriers like USAir Group Inc.

Technology helped create the business, notably Fed Ex's computerized tracking system that allows it to tell nervous customers the precise point in the pipeline that their particular package has reached. (UPS has since installed a similar system.) But in general, it was changes in demand and attitudes, not new capability, that brought the business into being. Many of the jets, in fact, are former passenger planes with the seats removed and windows covered, aircraft considered too out of date to carry human beings.

Fed Ex today has almost 400 aircraft, painted its trademark orange and purple. U.S. activity centers on the hub at the Memphis airport, where about 80 aircraft and 5,000 employees converge each night. Inside the vast hangar-like buildings, people and computer-controlled conveyor belts sort and ship out about 700,000 items a night. About 800,000 others are handled at other regional hubs at the same time.

Three hundred miles to the northeast, UPS, which owns 111 aircraft and charters 250 more, runs a similarly huge and frenetic late-night operation at the Louisville airport. The facility is cleaner than Fed Ex's, reflecting the no-nonsense, by-the-book approach that is almost a religion at the 82-year-old company. The smallest motions by human and machines are engineered and re-engineered. Trucks and cargo containers are washed daily; floors are kept spotless. "Packages are our honored guests," said William Beal, who heads pilot training for UPS.

Other contrasts: UPS's center is in general lower-tech -- its sorting is done by the human eye, not computers. And most of its people are union members, giving it less flexibility in assigning jobs and competing with nonunion Fed Ex. This fact has become a key issue in troubled efforts to reach a new contract with its main union, the Teamsters.

Fed Ex last year rang up sales of more than $5 billion. UPS's passed $12 billion, though much of that came from its traditional business of surface delivery by truck. The two companies' operations are predominantly in the United States but increasingly what concerns them is their stance abroad, where growth is faster (Fed Ex's was up 32 percent in the year that ended March 31) and the stakes are potentially much larger.

After long taking pride in growing through internal expansion, Fed Ex has shifted gears and gone on an acquisition binge to build itself up abroad. Last year it paid $895 million for Tiger International, a financially troubled U.S. air cargo line that did things the old way, hauling airport-to-airport rather than door-to-door.

Tiger brought to its new owners a fabulous asset, a large collection of routes to and between the growth economies of East Asia. The routes dated from the early '50s, a time when the United States held sway in the region and could have routes for the asking. Until the Tiger deal, foreign destinations to which Fed Ex flew were few indeed -- London, Brussels, Tokyo and Canada. With Tiger new ones were suddenly added: Hong Kong; Taipei, Taiwan; Osaka, Japan; Singapore; Kuala Lumpur, Malaysia; and Melbourne, Australia, were open, as well as Caracas, Venezuela; Frankfurt; and Rio de Janeiro. Fed Ex got 38 jets and 6,500 new pilots and employees from the deal too.

But it also got heavy debt, maintenance problems (many of Tiger's planes were aging) and an old-style air cargo business that has low margins. But Fed Ex hopes to turn things to profit by putting higher-margin, door-to-door packages on the new overseas routes, as well as continuing with the freight.

Fed Ex has bought 13 other companies since the start of 1989, primarily small ground delivery operations abroad in such places as Japan, Australia, Mexico, Italy, Britain and Germany. The idea is to keep the package in company hands for the entire journey. Picked up by a purple and orange van in Atlanta, it is flown across the Pacific and dropped at a Singapore doorstep by another van bearing those colors.

Fed Ex's entrepreneurial roots have helped it move quickly toward foreign opportunities. Yet UPS, once known for glacial-pace change, has found that it can move quickly when challenged. And it has found that it can live with the fact that the UPS way of life, in which everything including the depth of a driver's pockets is measured for efficiency, doesn't fit in every country.

"We have places where you may have a Buddhist shrine in an operating building," said UPS Senior Vice President John Alden. "... We're not going in with an iron hand and saying it's got to be done the UPS way and no other."

In 1989, UPS expanded international service from 41 to 180 countries, buying nine European-based transportation companies and one Asian carrier in the process. Last month it bought Seabourne European Express Parcels, a ground express operation that operates mainly in Britain but has routes on the continent as well. UPS's trademark brown vans ("Big Brown," the company is often called in the industry) now ply the streets of Britain, Poland and Hong Kong, among other places.

With its roots still in ground delivery, it is trying to position itself as a major trucking shipper within Europe. Customs checkpoints are meant to come down after the 1992 European economic integration. Distances there are often too short to make air delivery practical, so UPS hopes to clean up with cross-border trucking. "We have a very large ground operation within West Germany and we've begun to serve East Germany by the ground," said Alden.

For routes to the vast Asian market, UPS is having to go the hard way, via applications to regulators. It now flies to Hong Kong and Seoul, big-ticket destinations, but is still seeking permission for the largest one in the region, Japan -- $25 billion in goods moved by air between that country and the United States in 1988. To date UPS has had to lease space on other carriers, including Fed Ex, to reach Japan. UPS also began direct service into Mexico last year.

In 1987, UPS tried to become the leading international carrier in one stroke with a deal to purchase DHL. That deal fell through, however, and DHL remains the company to beat in the international arena. Looking outward since its founding in 1969 (its first flights ran shipping documents between San Francisco and Hawaii), DHL expanded quickly into East Asia and now claims to serve 187 countries (Mongolia was added recently).

DHL now has about 190 aircraft and leases space on other carriers for much of its cargo. It operates its main U.S. hub in Cincinnati with its main sorting center at Brussels, reflecting its foreign roots. Facing two able competitors that have much more financial clout (its annual sales are only $1.6 billion), DHL has just recruited some important backers, both to get money and to secure better access to cargo hold space and two of the world's most important economies.

Earlier his year, Lufthansa and Japan Air Lines each took 5 percent stakes in DHL's international arm, with options to expand to 25 percent each. Both are major air cargo carriers, but with little experience in the door-to-door side of the business. Now they will get it. In addition, Japanese trading house Nissho Iwai took 2.5 percent with an option for 7.5 percent. (The same three bought small stakes in the U.S. arms of DHL as well.)

DHL says that while it is not the largest express carrier, it is the most internationally experienced. "We've been out there 20 years now in most of those markets," said Pat Foley, chairman of DHL Airways, which runs aircraft for the system. "... Fed Ex and UPS don't have the name recognition." Fleets of fancy aircraft don't necessarily mean that things get there on time, DHL's fans say. Knowing how to get through customs can be important too.

With world commerce headed on a seemingly endless upward spiral, demand for rides around the world will only increase the seesaw battles between the express companies. Predicted Ted Scherck, president of the Colography Group, an Atlanta firm that studies transportation markets: "It's going to be even more tumultuous in the next five years."