ON MARCH 8, 1965, some 1,000 men of the Third Battalion, Ninth Marines splashed ashore at Red Beach 2, northwest of Danang. Heavy surf had delayed the landing for an hour, and the seas grew rougher as the landing continued. But the "grunts" were greeted by Vietnamese schoolgirls who bedecked them with flowers and by banners welcoming them to the struggle against Hanoi's mounting effort to take over South Vietnam.

Lyndon B. Johnson had sent in the Marines -- the first American ground combat units to go to Vietnam. He had crossed the Rubicon, but he did not yet want to admit it. His orders to Saigon: "The U.S. Marine force will not, repeat will not, engage in day to day actions against the Vietcong."

Even after the Marines were authorized to get into firefights, Defense Secretary Robert McNamara delayed (until June 1965) in authorizing use of U.S. Pacific area emergency war stocks or "mount-out" supplies. The Marines, as their numbers grew, ran low on aviation gas, rations, artillery shells, bombs and rockets. "That's what happens when you initiate a war but try to conduct business as usual in the United States," commented Col. Thomas J. O'Connor, chief of staff of the Marine air wing at Danang in 1965.

Through 1967, the Marines, fighting a tenacious foe in the northern (I Corps) region of South Vietnam, were repeatedly bedeviled by insufficiencies of helicopters and men, to say nothing of Johnson administration constraints on strategy and tactics.

Such insights crop up repeatedly in these first four slim volumes of the Marine Corps' own illustrated history of its experience in Vietnam. The authors trace the 1954-64 advisory period, the 1965 troop buildup and early anti-guerrilla operations, the 1966 turmoil in South Vietnamese politics (which put the Marines in the middle), the bloody 1967 battles along the DMZ on the eve of the communists' 1968 Tet offensive and of the siege of Khe Sanh. More than 6,000 Marines, along with uncounted enemy, had died by the end of 1967 -- in scores of places like Hill 881, the Queson Valley, Con Thien, the Arizona Territory and Go Noi Island. Helped by good maps, the Marine historians describe the battles, often down to squad level, with names, dates, places, units, numbers, the intentions of the high command, and the comments of the participants.

One participant was the present commandant of the Corps, General "P.X." Kelley. As a lieutenant colonel, he led his battalion in "Operation Texas" near Quang Ngai in March 1966. His superiors thought the opposing North Vietnamese regulars had fled west toward the mountains. Kelley suggested that the enemy might have done "the reverse of the obvious" and headed east. He turned out to be right; his troops ran into the foe at Phuong Dien (2), a typical fortified hamlet with barbed wire, deep bunkers and trenches. It was a seesaw battle. Kelley's hard-charging rifle companies were soon down to half-strength; Kelley himself got caught in the cross-fire. After taking heavy losses, the enemy slipped away during the night, to refit and fight again.

SUCH was often the story. Partly for lack of men and helicopters, the Marines rarely surrounded an enemy unit during those early years. Their officers were frustrated; often half the Marine losses came from mines and booby traps. Repeated Marine sweeps of the same populated areas -- prior to the decimation of Vietcong cadres at Tet in 1968 -- did not bring much village security in I Corps.

All this as well as individual heroism the Marine historians make clear through compelling detail. They also illuminate the debate between senior Marine generals and Army General William C. Westmoreland, the overall U.S. commander in Vietnam. The Marines thought Westy's emphasis on chasing enemy Big Units in the jungle was a waste of effort; "concentrate on the populated areas and let the enemy come to us" was the Marine argument. Westy's plan in 1967 for a "McNamara Line" of fortified outposts, electronic sensors and minefields below the DMZ roused even less enthusiasm among the Marine commanders who had to put their troops into static positions, hostages to enemy artillery fire. And, contrary to the impression given by CBS's recent melodramatic documentary, The Uncounted Enemy, charging that Westy deliberately undercounted communist manpower, the Marines felt that Westmoreland's staff usually overestimated the foe's strength, at least in I Corps.

Like other official historians, the Marine chroniclers do not tell all. The removal of a lackluster unit commander, for example, must be inferred; the narrator merely records that a successor arrives to take over in mid-battle. No assessments of Marine tactics are made, except implicitly, and the generals do not get passing or failing grades.

But the Marine historians tell us a lot that we can't find elsewhere. This is not drum- and-bugle history. These researchers have unique access to the Vietnam war's classified archives (although they still can't get Pentagon clearance to use some items). They provide a detailed operational chronicle -- the basics -- on which all other serious historians must draw. Like their unsung counterparts in the other services, they supply an antidote to TV docudramas and facile academic or political post-mortems. Vietnam veterans should be grateful, and so should the rest of us.