LOST IN THE BATTLE of the titans to take over Marathon Oil has been the deep and sometimes irremediable loss any city suffers when a major home-based industry falls to outside ownership.

In Findlay, Ohio, the town of 36,000 that was born and grew with Marathon, the townspeople fear that Mobil would close down Marathon's headquarters quicker than one can say "oil well." All 2,400 jobs at Marathon would be jeopardized, since Mobil's prime interest is in acquiring Marathon's huge oil reserves.

And, says Findlay Mayor Bentley Burr: "The value of Marathon to this community lies in more than just dollars. How do you calculate the value of the leadership Marathon employes have given the town, to civic organizations, the contributions to the quality of life?"

So Marathon and Findlay have found their would-be "white knight" -- U.S. Steel. "Welcome U.S. Steel," says a flashing sign outside the city hall. "At least we think this is a company that isn't going to turn Marathon's headquarters into a parking lot," a local stockbroker told the Associated Press.

Perhaps so. Certainly U.S. Steel wouldn't be in a position to fire all of Marathon's oil industry experts. It would need their skills. But what of the bookkeeping, personnel, payroll functions that any corporation can perform? The common takeover pattern is that firings start in 12 to 18 months -- promises to keep the old staff intact notwithstanding. Headquarters start looking for ways to maximize the profits of subsidiaries, and duplicate staffs are an inevitable target.

Then everyone else in the city starts to suffer. Bank accounts, legal work, insurance, advertising and accounting services are transferred away. From the United Way to the arts to downtown development, essential leadership is lost. With job losses and property abandonment, everyone's taxes escalate.

The 1981 business merger boom -- running at a level of unprecedented billions of dollars -- is like an arrow aimed at the economic health, government solvency and civic leadership of every city in America with businesses that might be ripe for takeover.

It's not weak or poorly managed firms that corporate giants seek to swallow. Rather, they are looking for profitable, conservatively run companies with a depressed market price for their strong stock, balance sheets and market positions. The sad fact, says Marquette University professor Peter Marchetti, is that good management can easily lead to extinction in a world dominated by "conglomerates for whom capital in the abstract is everything."

Sadder still is what so often happens to acquired firms. Sometimes -- as in the notorious takeover of Youngstown Steel by the Lykes conglomerate -- the big corporation just uses its new property as a "cash cow," milking its profits and investing them elsewhere. Eventually, the weakened plant is shut down.

Or the conglomerate may set an arbitrary profit or market share the subsidiary must achieve. If it fails, it is simply closed down and the parent company moves on to seek better investment elsewhere. By contrast, home-city company owners accept good years with bad and may be satisfied with much more modest profits.

The unhappy fate of acquired firms -- and their home towns -- was dramatized last year in a national survey of corporate takeovers by the U.S. House Small Business antitrust subcommittee. "Conglomerate mergers do not create new productive resources and rarely develop new markets," the subcommittee found. "The rates of job creation, productivity and innovation slow after independent companies are absorbed."

Alfred Dougherty, then director of the Federal Trade Commission's bureau of competition, told the subcommittee: "A conglomerate -- lacking community loyalty -- can simply write off a line of business, a plant, a work force, or a whole community and can turn its attention elsewhere, leaving others to pick up the pieces."

Other witnesses came from cities in Massachusetts, Virginia, Ohio and Maine to tell just how that happened to them. One of the most disturbing stories was told by Hopedale, Mass., Town Administrator Bernard Stock. Draper Looms, which had employed 2,400 of the town's 4,000 residents, used to contribute 30 percent of the town's property taxes. Founded in the 19th century, it had built the town hall, high school, country club, airport, railroad, sewage plant, power facility and even donated land for the town cemetery.

But in 1967, Rockwell International acquired Draper Looms. Stock told how the executive staff was moved to Pittsburgh. "We no longer had someone in the town of Hopedale who could make a decision on company/town- related problems." Research, development and maintenance staffs were cut to the bone. The building began to deteriorate. Some $30-40 million of Draper corporate savings were transferred to the parent company. Managers were rotated through the plant. The factory was gradually closed down, its workers discharged. The town lost hundreds of thousands of dollars in property taxes.

"They made a valiant attempt to run a business they knew nothing about and took the business and us down with them," said Stock.

Small wonder, then, that critics of the merger mania suggest big companies use their cash to reinvest in their own operations, instead of acquiring viable companies and then shuttling jobs from hard-pressed cities to remote rural areas and the Third World.

Sad to say, though, all seems now to aid the merger boom. Six oil companies alone got banks to advance a staggering $25 billion in lines of credit during the recent Conoco takeover bids -- a sure inflationary pressure. Big companies also persuaded federal courts to overturn several state statutes written to slow takeover bids of resisting corporations.

And the Reagan administration's new antitrust chief, William Baxter, proclaims: "There is nothing written in the sky that says the world would not be a perfectly satisfactory place if there were only 100 companies." Teddy Roosevelt must be spinning in his grave!

Perhaps the time has come for a new patriotism: one that recognizes, as the House Small Business subcommittee suggested, that "the national interest may better be served by strengthening the role of independent businesses in the economy, as they are the most productive, the most innovative and the most prolific job-generating sector."