In the morning paper, in this peace capital of America, after return-of-the-hostage stories had begun to play out in the press, a large picture of a Marine dominated page one. He was in combat garb, camouflage helmet and all, with two belts of machine gun ammunition slung over his shoulders and criss-crossing his chest. His look was properly grim. The headline with the photo read: "GUNG HO."

Inside, two full pages were devoted to more pictures and a lengthy article about just-completed maneuvers by 6,000 Marines in California's Mojave Desert. The exercises tested U.S. combat readiness against Soviet forces in the Mideast, the article said; the Marines, as the shock troops of the larger overall American Rapid Deployment Force being trained to protect vital U.S. oil interests in the Persian Gulf area, would bear the initial brunt of the fighting. They would lead the way in any U.S. action in the desert hotspots. And they would form an elite unit to deal with any new acts of terrorism, such as the seizing of more U.S. hostages.

The mock war exercises in California were the first staged in the new administration. After four days of skirmishing across the desert floor, with tanks, armored personnel carriers, close air support and infantry, all using live ammunition, the Marines were said to be razor-sharp and spoiling for a fight.

"Three years ago I never thought I'd see another war," The San Francisco Chronicle quoted a Marine colonel as saying. "But I think we're going to be tested severely in the next decade. It's a great time to be a Marine." Others, echoing the words of an Army reservist here who says his unit has been told to "get ready," expressed eagerness to test their combat skills in real life. "I came into the corps to fight," said a young Marine corporal who had enlisted when the hostages were seized.

All this martial fervor comes amid simultaneous page one reports from Washington about a tough American line spelling out new determination to use force if necessary in the period we are entering. The new secretary of defense Caspar W. Weinberger, says the nation needs substantial increases in defense spending and higher production rates of weaponry. The new secretary of state, Alexander M. Haig Jr., says international terrorism replaces human rights as America's primary foreign affairs concern, and bluntly warns the Russians against continuing to promote worldwide terrorism. The new president of the United States, Ronald Reagan, denounces the Soviet Union and warns of dire consequences if its troops march into Poland.

Talk of new bombers, new nuclear-powered aircraft carriers and new strike forces dominates the news as the new president warns the world that "never again" will the United States permit its personnel and its national honor to be humiliated as it was during the Iranian hostage crisis.

Even as the cheers from our continuing celebration over the safe homecoming of the hostages reverberate across the nation, bringing a new surge of pride in country and spawning old-fashioned displays of flag-waving patriotism, the aftermath of their return appears to be creating a stiffening of American resolve -- and a "let-the-world-take-note" warning of the lessons we intend to draw from this episode.

New winds are blowing from Washington. And they are calculatingly cold.

Perhaps not in a generation has such a climate of genuine national unity existed, and certainly not since the days before Vietnam and Watergate has a president commanded such a national audience of people disposed to think well of his words and acts. However transitory the national glow may prove to be, and however long people continue to respond to their president's directives, for the moment the spirit of good will is real and welcome.

Few would argue that the new militancy -- or new realism -- about the country's role in the world is undesirable. Nor that doubts about the nation's ability to carry out desireable military goals are unjustified. America has been awash in pessimism, doubt and frustration for far too long; those public perceptions about American weakness held by so many have been borne out all too often in recent years.

For a time, reaching the apogee during the hostage crisis, it seemed that everywhere you looked you found new evidence of failure. From the blowup of our missiles in their silos to the wreckage of our helicopters in the Iranian desert, it was clear that something was seriously wrong. So, if the agonies endured by the hostages in Iran and the Americans at home who shared in their suffering produce a new determination for national strength and military effectiveness, all to the good.

But it would be tragic if these were the only lessons learned from our hostages in Iran.

To this reporter, their attitudes have been the most impressive thing about the former hostages. Aside from a remark or two about going back to Iran in a B52, nearly all have been remarkably philosophical when speaking publicly about their experiences.

With modesty, good humor and seriousness they have shunned any heroes' role in which the populace wants to cast them. Their words have been notably tempered. If they have any desire for vengeance, or wish the nation to retaliate because of the way they were treated in captivity, they have kept those feelings to themselves.Indeed, they have cautioned press and public to be careful in using such terms as torture. They do not hate the Iranians, many of them have said, and they have tried to place the Iranian experience in historical perspective.

From first to last they have acted like responsible, self-effacing, dedicated public servants -- and they have not seemed to think such behavior is in any way unusual. They have acted, as some of them have said, the way bureaucrats like them should perform. If their fellow citizens at home will think about it, these 52 Americans who have returned to freedom might just be demonstrating something more important than old-style saber-rattling heroism. By their example, they are showing that the much despised and deprecated federal service, bureaucrats and all, can be worthy of the highest respect.

Let that sort of feeling of pride in public service sweep the country, and we could have at last a government as good as the nation it serves, operating in a new era of good will. That would be a war worth winning.