ONE of the traditions of American humor in fiction at its most successful involves the fusion, at the focus of some bizarre incident, of laughter and horror. Faulkner showed his mastery of the technique in the Snopes trilogy, and Ralph Ellis in "Invisible Man." In war fiction, Kurt Vonnegut's "Slaughterhouse Five" and Joseph Heller's "Catch-22" have added an absurdist dimension to the technique. In "Rising Like the Tucson," Jeff Danziger, the Monitor's editorial cartoonist, applies it to the Vietnam War and shows himself a master. But while nearly everything that happens in "Tucson" is in some way absurd, the book itself is not absurdist. Its wild events remain within the vision of a world that purports to have values, to manage itself with a degree of sanity, to show kindness, to have some limits (though not many), and some reserve (though not much). This vision reflects the surrealism so many young Americans felt while in Vietnam. Nothing made sense. But it should have. The world itself was still a place with, if not rules, gene ral outlines of what decency should be, though war behavior showed its inverted image. Lieutenant Kit, Danziger's central character, is generally acknowledged to be a useless officer. Made a lieutenant because he supposedly speaks Vietnamese, though he does not, he bumbles his way through his tour of duty at Phuoc Vinh - an American base in Vietnam - during the Vietnamization period of the war, as the somewhat corrupt and increasingly demoralized United States Army slowly backpedals out. If Lieutenant Kit doesn't grasp much of what is going on, he is simply a more extreme example of everyone in the novel, including the North Vietnamese, to a degree. Not only do the book's plentiful drunks stumble uncom- prehendingly through events. So does nearly everyone else, including Kit's father - a real-estate investor from Connecticut who has decided that once the US has won the war, Saigon will be a hot place to invest in. He tries to involve his son in an elaborate scheme to buy up large sectio ns of the city to be developed into hotels, malls, and golf courses. This subplot rushes together with the continual murder and mayhem of the main action at the book's crisis, yet even then Kit meanders his way, innocently and ignorantly, through it all. This is a crux in the novel. While wreckage, physical or mental, is made of nearly all the other characters, the pivotal one wanders offstage basically little-touched, as though numbness is one of the key conditions of survival. The climax that does not happen, that slips by in the chaos of a major North Vietnamese attack, has a curious, anticlimactic effect on the book. Danziger writes exceedingly well. His descriptions are crisp, resourceful, and economical, his humor continuous. The language of his fighting men is plentifully profane, while the more useless and pencil-pushing officers speak courteously and reflect an abstract order almost dainty at times and generally functionless. Danziger's vision of the war has much in common with such films as "Apocalypse Now," such books as Michael Herr's nonfiction "Dispatches," and Tim O'Brien's novel "Going After Cacciato." All depict values tossed into a whirl of madness, but while the approach in "Apocalypse" is mythic, that of Herr kaleidoscopic, and of O'Brien surrealistic, Danziger offers mordant humor. The effect is often powerful and wrenching. Danziger's fictional world is vivid, moving, and full of precise touches. It makes one laugh while feeling guilty for laughing, driving home the bewilderment that the soldier in the field must have felt daily. "Rising Like the Tucson" will surely join the shelf of Vietnam novels as an equal and contributing vision of the time America's containment policy went massively awry.