Now we know. The great lesson of the war in Vietnam is that fighting without a clearly articulated objective will leave hack moviemakers in astae of confusion and lead inevitably to war movies as stupefying as "The Boys in Company C."

The best thing to be said for this blithering, disjointed chronicle of a group of Marine recruits from boot camp to combat duty (of a sort) in Vietnam is that it scrapes bottom. It will require truly subterranean ineptitude to sink lower."The Boys in Company C" gets the heralded cycle of Vietnam movies off to such a flying catastrophe that everything tht follows is bound to look relatively respectable.

What possessed the people who contrived this cinematic nutcase? It's as if director Sidney Furie had decided that because the war in Vietnam was senseless, he would make a senseless movie about the war in Vietnam. Even this desperate specualtion may be giving him more credit than he deserves.

The finished film has no thematic or emotional integrity. It flip-flops withdesperate hypocrisy between clownish antics and indignant orations. As an action director, Furie is a rare duffer.Whenever a mortar explodes, you keep waiting for the other shoe to drop. Maybe there was an ammo shortage after Clint Eastwood got through with "The Gauntlet."

The most striking characteristics of Furie's folly is its vociferousness and total lack of control. Furie must have been carried away by the Marine Corps drill instructors he hired for the boot camp sequences. The actors scream at each other so much that you can't help wondering if the director spent most of his time screaming at them.

The filmmakers must have spent more time contemplating old war movies than researching the war in Vietnam. The scenario is a mishmash of bits and reflexes from "See Here, private Hargrove" through "The Dirty Dozen" and "M*A*S*H*," with a crib from civilian melodramas like "The Longest Yard" and "American Grafffiti" thrown in here and there. Needless to say, Furie fails to achieve a brave new synthesis. "Boys" is not so much a new departure in war movies, reflecting the controversial nature of American intervention in Vietnam, as a collection of hand-me-downs tailored by some loud mouthed, incomprehensible crank.

The "boys" are an adaptation of the old ethnic crosssection in the Hollywood war movies. The strangest adaptations are a hippie pacifist Marine played by Craig Wasson and a black pusher played by Stan Shaw who is given most of the morally superior speeches although his main interest in Vietnam is supposed to be the drug traffic. At least his contact was reassuring: The sadistic Japanese officer has eturned as a South Vietnamese. It will probably be this sort of innovation that earns Furie brownie points in some quarters for taking a hard-hitting approach to the war.