In March 1965, 3,500 U.S. Marines landed in South Vietnam. By year’s end, there were 200,000 of them. When LIFE dispatched Associate Editor Michael Mok and Photographer Paul Schutzer to spend six weeks with them, the two men found the Marines mired in a world of ambiguity: They were at once dispatching lives and saving them, hailed as heroes and decried as villains.
Mok and Schutzer risked their lives to bring LIFE’s readers a 22-page photo essay on the “blunt reality” of the war—one that, Mok wrote, vividly called to mind scenes from Saipan in World War II and Inchon in the Korean War. “Only the locale is different, and this observer, now a generation older. No one used to call him ‘Pop’ or ‘Sir’ in the old days.”
The scenes the men captured, in images and words, reflect a world in which bullets and bandages were doled out in equal measure. The Marines carried out their missions, killing and capturing Viet Cong soldiers, but they also undertook a broader mission to win the hearts and minds of the people whose world they occupied. Treating the Vietnamese with dignity was as much a matter of human decency as it was a strategy to win the war: To acquire crucial intelligence from villagers, the Marines needed first to earn their trust.
The essay’s most enduring images are not those that portray scenes of battle and warfare, but those that capture the humanity of people embroiled in a situation not of their own making. There’s the Vietnamese mother carrying her wounded baby through her besieged village, and the U.S. Marine who scoops him up to get him to a medic, to no avail. There are Marines handing out dolls to children who have nothing, and children ripping them limb from limb, preferring the disembodied head of a doll to no doll at all.
The magazine chose a face to encapsulate the humanitarian side of American forces, and that face belonged to Hospitalman Second Class Josiah Lucier, 29. Nicknamed “The Doc,” Lucier’s primary job was to keep the Marines healthy. But, Mok wrote, “then there is the job he does because he wants to, which is holding sick call for all the villagers within walking distance.” Lucier treated his patients, especially the children, with a tenderness that’s palpable in photographs.
But he wasn’t Pollyannaish about the world he’d been living in for three years. Lucier carried a gun when he made house calls, never knowing where the enemy lurked. “I am a humanitarian and all that jazz,” he said, “but I am not completely out of my ever-lovin’ mind.”
For wartime readers, these images matched images of the faceless enemy with universal pictures of love and loss. They show another side to the soldier who might return home to be spit upon and scorned, a recipient of misplaced hatred.
The Marines, for their part, didn’t need to be greeted with protest signs to grapple with the gray area in which they lived each day. They had already internalized it. Said one, “Sometimes I feel like one of the bad guys … When we go into these villes and the people look at you in that sad kind of way they have, it’s pretty hard for me to imagine I’m wearing a white hat and riding a white horse.”
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.