THE UNITED STATES has fought in nine major wars so far. We average a war every 23 years. Only two of them, however, have yielded much good fiction. No one at all returned from the Revolution or the War of 1812 to write a memorable war novel -- or an unmemorable one, for that matter. No American. One or two Englishmen did. The first good Civil War novel didn't come along until 1895. There has been no novel of importance about the Korean war yet, or even a good movie. (M*A*S*H, you're thinking? Doesn't count. It only pretended to be about Korea. The mood it portrayed was pure Vietnam.)

Only World War II and Vietnam have produced large quantities of good fiction. But they -- they have produced enough to make up for all the rest.

It's still too soon to start ranking novels about Vietnam, just as it seems to b too soon

for the country to agree on

the meaning of the war itself. But World War II is now 40 years in the past, and its fiction can be seen in perspective. There is plenty of it to see. Well over a thousand American novels have been written about the war . . . and new ones still appear. I've counted five in the last two months. No final word can therefore be spoken. There may yet be new masterpieces.

But that granted, a solid body of work is in place. Of the thousand-plus, how many are classics? How many others are at least very good, still worth reading in 1985? And how many are has-beens, praised and popular when they came out, maybe still bearing famous names, but now clearly due for demotion?

The quick answer is that there are four World War II novels that seem assured of a place in our literature, two more that remain strong candidates, and another half-dozen that are well worth reading (if you like war novels). There are also eight or 10 once-praised novels and one famous book of short stories that can now be seen as minor, or in some cases even less important than that.

None of these figures should be taken as precise. I doubt if anyone has read the whole thousand-plus. Certainly I haven't. Even if I had, my judgments would remain subjective, judgment coming in no other form. But with a little help from books like Holger Klein's The Second World War in Fiction and Wayne Miller's An Armed America and Colonel Jesse Gatlin's The U.S. Air Force in Fiction, I think I have come to know most of the distinguished and once-distinguished work.

Novels about the war began to appear, of course, long before the fighting ended. Most were junk, and recognized then as junk. But in 1944 two American war novels came out that appeared to have real merit. They were similar in that both dealt with the Italian front, different in all other ways.

Harry Brown's A Walk in the Sun is a combat novel, so short as to be really a novella. It tells the story of a single platoon on a single day -- the day of an invasion. No officer figures in the main story. The platoon's lieutenant managed to get himself killed while still on the landing craft, and the platoon encounters no officer on shore. It's the interplay among the sergeants and privates -- who carry in their way responsibility as great as any general's -- that brings the book alive. That and Brown's great gift for dialogue. The book seems a true slice of war, and it is as vivid now as on the day it was published. It is also too slight to be an actual masterpiece.

John Hersey's A Bell for Adano describes a liberated Sicily. American troops have captured the town of Adano, and Major Victor Joppolo of the U.S. Army is now governing it in place of the former Fascist mayor. What do the townspeople experience? Joy. Democracy. Good government. And a few misunderstandigs. The town blossoms under the major, and the townspeople can't get over how wonderful Americans are. Delightful reading in 1944.

But in 1985 a reader is more inclined to wonder how such a book could have made John Hersey so famous and won him a Pulitzer Prize. There are two problems. One, of course, is our changed national mood. We don't quite so readily see ourselves as wonderful now. That's not John Hersey's fault. The other problem is. He simply did not yet know how to write fiction. With one exception, the characters and events in A Bell for Adano are all real (Major Joppolo, real name Frank Toscani, later sued Hersey), and they first appeared in an article he wrote for Life magazine. When he attempted to transform them into fiction, they all turned to cardboard. A Bell can now be read only as a period piece.

No war novel of significance came out in 1945, but the year after there was a flurry of promising work. Alas, it can all be dismissed now. Thomas Heggen's Mr. Roberts, a novel about the Navy in the Pacific, captured a certain postwar mood of irreverance toward officers and regulations. Gore Vidal's first novel, Williwaw, has the difference of being about the Aleutian Islands and some of the simple- minded charm of the school of writing called naturalism. That is, every character is inarticulate and limited to a maximum of three thoughts. Robert Lowry's Casualty, another novella about the army in Italy, has a lot of irony and two good scenes. It needed more.

Another four well-received books came out in 1947, and three of them can also be dismissed. Vance Bourjaily's first novel, The End of My Life, is well, even beautifully written -- too beautifully. The book is sensitive, literary, Hemingwayesque. It's about a volunteer ambulance driver in North Africa, and only a born novelist could have written the dialogue. But only a callow youth (Bourjaily was 24 and exceptionally callow) could have been so moonily romantic.

James Michener was not callow at all in Tales of the South Pacific. Michener, already 40, had studied at nine universities, taught in the education departments of two, and published about 15 articles in journals of education. The style of Tales reflects that background, as it also anticipates the quarter century of writing he was about to do for The Reader's Digest. That is, the book takes simplistic approaches, and it is 90 percent tell to 10 percent show. Why then did it win the 1947 Pulitzer Prize? Well, it does have a confident ring of authority and a belief in its own clich,es. One would also have to add that the Pulitzer committee gave the prize to the wrong book. Michener has done better work since.

John Horne Burns' The Gallery is a much more complicated case. This is another account of the war in Italy. It's as mannered and elaborate as Tales is simplistic, and people either love it or hate it. Those who love it have kept it a cult book ever since it came out, and consider it major work. Me, I'm one of those who hate it. That's partly because I can't stand to see Burns being openly cruel to those of his characters he dislikes and openly tender to those he favors. Creators should be more detached. And it's partly because I weary of his eternal knowingness. (If he would occasionally not write the word "smart" as "smawt,' I could forgive much.) But judge for yourself. "Brigadier generals flounced along the streets like democratic abbesses," Burns writes in a typical sentence, describing Washington in 1943. If that amuses you, you will enjoy The Gallery. If not, not.

Finally, William Wister Haines published Command Decision in 1947. It's a novel about the U.S. Air Force in England. The main character is Brigadier General K.C. Dennis (he never flounces, isn't democratic), commanding the Fifth Bombardment Division. It is almost a very good book. The reality of the air war is overwhelming, ad there are sergeants as vividly drawn as generals. Only Haines's taste for melodrama keeps this from being major work.

MAJOR WORK appeared the next year, and in quantity. Nineteen Forty-Eight was the annus mirabilis for World War II novels. Irwin Shaw published The Young Lions, Norman Mailer came out with The Naked and the Dead and James Gould Cozzens published Guard of Honor

Shaw's book, though honorable and well- written, does not hold up. To read it now is something like looking at WPA murals in a 1930s post office. Everyone seems too clearly to be fulfilling a symbolic role. And yet the painting remains impressive.

The Mailer and the Cozzens are, of course, two of the masterpieces of our literature. Guard of Honor is the best book ever written about the Air Force (though it's not for people who can't handle complexity, or hate the idea of growing up). The Naked and the Dead is one of the best books ever written about the infantry. These two between them constitute half of the classic American fiction about World War II.

Nothing special happened in 1949 or 1950, but 1951 was another banner year. A competent book, an almost-great book and an absolutely great book about the war came out.

The competent one is John P. Marquand's Melville Goodwin, USA. Major General Goodwin (he commands an armored division) is brilliantly observed; and if the rest of the book were up to the character study of the general, this would be a major work. But Marquand's fate was to cease to believe old truths without learning any new ones. Once he grew old enough so that mere animal high spirits no longer supported him, he tended to write books that were exhausted and even querulous. Melville Goodwin is such a one.

The almost-great book is Herman Wouk's The Caine Mutiny. It may yet turn out that we can drop the "almost." In terms of sheer narrative pull, it is the strongest of all World War II novels, and it has real profundity as well. Asked to name a fictional character from World War II, most people are apt to mention Captain Queeg. What damages the book is that Wouk twice -- and in key ways -- manipulates probability in what is otherwise a realistic work. That no one at all among the Caine's crew should back Maryk and Willie Keith at the time of the court-martial makes for drama, but on the book's own terms it is quite unbelievable. So is May Wynn's background. The Caine Mutiny's Pulitzer nevertheless is richly deserved, and the book seems likely to endure.

The great book is James Jones's From Here to Eternity. It seethes with faults. It's far too long, because many of the scenes are far too extended. It's far too ambitious. Jones tries to get every single truth he knows about human nature (and he knows a lot) into that one book. They don't all fit. At times he's absurdly romantic. But all that said, here is not only the best book about life as an enlisted man that I have ever seen, here is stunning originality. Jones was self-educated (he went straight from high school to a six- year army hitch), which means that his insights are all his own. That gives him a power one seldom acquires at a good prep school -- or at nine universities, for that matter. An infantry company was his Harvard and his Yale.

The next considerable war novel came along in 1953, and that was Leon Uris' Battle Cry. Uris intended an epic, and he unquestionably has enough characters, events, scope, etc., for two or three epics. He even gives a pretty good account of basic training in the Marines. But if the characters in A Bell for Adano are cardboard, the ones here are some kind of plastic. The Marine Corps deserved better, just as the Army in the Aleutians deserved better than Williwaw.

We're nearing the end now. There's a long gap until 1959, in which year John Hersey redeemed himself. He published The War Lover, a novel set in the same milieu as Haines' Command Decision -- a U.S. bomber base in England. The title is dreadful. The book itself, a study of a pilot thrilled by combat and by inflicting death, is almost great. It does have a series of awkward time-jumps. I nevertheless think it has almost as good a chance as The Caine Mutiny of becoming a permanent part of our literature.

THE AIR FORCE, already rich in good fiction, got still another treatment two years later -- one that its leaders could perhaps have done without, but that the public certainly could not. In 1961 Joseph Heller published Catch-22, the fourth classic American novel about World War II. Its very title has entered our language, and the novel itself has an assured place in our literature. I take it for granted that to give a thumbnail sketch of it here would be something like telling an audience of teen agers who the Beatles were. Superfluous information.

One more majr novel has appeared since Catch-22, and that is John Oliver Killens' And Then We Heard the Thunder, which came out in 1963. This is a story of black soldiers in the Army, starting with their arrival at a reception center. It is no fun at all for white supremacists to read, because these black privates keep deftly weaving in and out of the military code in order to cope with and even triumph over the white officers who on paper have every advantage. It is wonderful and subversive and delightful for everybody else.

So. A dozen World War II novels still worth reading, and another eight or nine once-distinguished ones that perhaps can be skipped. But I'm not quite done yet. I want to mention two more books. One is a World War II novel, but not American. The other is Amrican, but not a novel.

Hans Hellmut Kirst published The Officer Factory in Munich in 1960. The American edition came out in 1963, in a superb translation by Robert Kee. As the title suggests, the book is about an officer candidate school. This one just happens to be German. The action takes place in 1944.

Like Catch-22 and And Then We Heard the Thunder, The Officer Factory is black humor, though with a different flavor than either American book. And like them it is at bottom profoundly serious. I love it. If it were only American, it would be high on my list of very-goods.

Bill Mauldin published Up Front in 1945. That's long enough ago so that there are some unfortunate people who have never heard of it. Mauldin's cartoons about Willie and Joe, two unshaven infantrymen in Europe, are as good as any novel, just different. The text he wrote to accompany them sparkles to this day. The book is still in print. Get it.