MAJOR ANDRE' By Anthony Bailey Michael di Capua Books Farrar, Straus and Giroux. 200 pp. $15.95

THE MAJOR ANDRE' in Anthony Bailey's novel was adjutant general of the British forces in New York. In September 1780, his superior, Sir Henry Clinton, sent him up the Hudson to negotiate with General Benedict Arnold, the Continental commander of West Point, the betrayal of that strategic post on the Hudson to the British army.

There is an axiom that if you intend to write fiction about great historic events, you should concentrate on the minor witnesses rather than the major participants, for it is the aides and spear-carriers who can be used to cast the most curious light on the renowned and the notorious. Bailey obeys that axiom in his deft novel. For the young Andre' is nearly like an innocent bystander -- he is to carry back General Arnold's offer of a deal to the British. It is a deal that would do credit to any sporting or show biz contract, and covers payments even in the eventuality of West Point's not falling to the British. After his meeting with Arnold, Andre' folds up the deal that has been written out by Arnold and puts it in his boots.

Then, more or less to suit the convenience of Americans who may or may not be pro-British, he agrees to return to New York overland. Of course, for the sake of his guides, he consents to exchange his red military coat for a plain civilian one.

From that point on we are engrossed by the sense of a great darkness overtaking a genial, witty and lusty young man -- a darkness that will offer him little, since we know he can never become a hallowed martyr like the Yale man, Nathan Hale.

There are two other techniques, other than the bystander technique, that Anthony Bailey uses with some skill. The first is to have the victim, Major Andre', directly address -- from start to finish -- this or that particular Continental officer. This device could if less well handled seem quirky and tiresome, but through it here we become friends with Andre' and involved in the questions of his survival and his personal honor.

Secondly, Andre' talks to us in the idiom of his time, as far as it can reasonably be judged from journals and plays of the period, without our ever feeling an embarrassment or sense of willful oddity.

There is an occasional lapse into triteness, as when Andre' compares his perilous situation to that of a caterpillar journeying up and down a leaf. There are also one or two sentiments that seem to fall away into historical hindsight, as when Andre' observes, "An excessive interest in land speculation and financial gain seems to be a vice not limited to merely one general. Your cry for freedom sometimes seems to be a cry for the right to make money untrammelled by responsibilities." But then I suppose Bailey, an English expatriate, could justly observe that the American Revolution was a very mercantile affair.

THESE ARE minor faults in a work of considerable grace. One of Bailey's successes is in conveying the intimacy often existing between officers on both sides. Nearly every Continental official Andre' speaks to seems to share a mutual friend with him. Andre' has even had some sort of romance with Benedict Arnold's young wife, a Philadelphia woman named Peggy Shippen. And allegiances don't seem as firmly placed as they are in the history books. The roads down to Tarry Town are plagued by hoodlums called Cowboys and other marauders whose loyalty swings either way. By an irony it is Cowboys who apprehend Andre' and discover the mysterious papers in his boots.

By that point we are engrossed in what happened to a young Anglo-Swiss officer on the now freeway-spanned reaches of the Hudson more than 200 years ago. That is in part because it's an old and yet eternally recurring story: a promising young man becomes an embarrassment both to his captors and to his own people, the handlers who sent him off on a strange mission.

As everyone knows, the cold General Arnold evaded any palpable punishment. Bailey's portrayal of him makes you feel that the universal execration of his name is merited. For poor young Andre''s sake, as well as for the Republic's.

Thomas Keneally's next book, "The Playmaker," will be published in September.