You can almost hear the Beach Boys playing in the background in the long-ago snapshot of four young guys in crew cuts posing on a California beach as waves crash behind them.

On the other side of the water, a war waited. It was a faraway place named Vietnam just coming into American consciousness, a conflict metastasizing into full-blown war.

The four were Marines in training and that off-day at Oceanside in May 1966 was a pleasant respite to the rigorous and condensed training at Camp Pendleton, where the military hurriedly got warm bodies ready for the fray.

Tom Hanks, standing in the photo with his back to the board, doesn’t remember trying to catch a wave. Instead the board was a backdrop to record their cocky playfulness and youthful muscularity.

Hanks (who was in Vietnam three decades before Forrest Gump) was from New York. Bob DeVenezia from New Jersey, was a non-stop needler. Bob Falk, from Pennsylvania, was the low-key dude. Dennis Puleo, from New England, was the guy with the outsized personality (and the fellow yelling in the photo.)

The boys were being trained to kick ass, to be killers, although the beach photo captures a moment of innocence, a calm before the maelstrom.

Hanks and his buddies didn’t know much about Vietnam other than the Communists needed to be stopped. The idea of combat was a vague notion that enveloped them as they grew up in the wake of America’s greatest victory.

“I was raised in the Fifties, you had World War II movies with John Wayne,” Hanks said. “We played war in the woods.”

Hanks, a retired finance executive in Sandy Springs, gathered with his three comrades last weekend in Florida where they again borrowed a surfboard and mugged for the camera.

It was 50 years since that moment. The men, all either 70 or approaching it, are the oldest Baby Boomers and among the first few waves to fight in what became the nation’s longest and most bitter war.

Within three months of the 1966 snapshot, they would be terrified grunts getting helicoptered into teeming jungles from the decks of the aircraft carrier USS Iwo Jima.

On their first night, they were flown into a zone where the Viet Cong supposedly operated. They dug in for the night. Of course, it was raining.

“They put me in a listening post, 50 yards outside the perimeter,” Hanks said. There were trees falling in the jungle and odd sounds in the night, broken up by constant shooting, mostly from fearful newbies blasting into the dark unknown.

“You think you see things,” Hanks recalled. “We were just kids. We were shooting like crazy. It was all about survival.”

In the morning, they learned a Marine had been killed, shot by a fellow Marine who finished him off with a grenade.

Hanks was summoned for a task: Body detail, he had to bag his comrade’s body for evac.

He then realized this would be his existence for the next year.

After 10 missions from the Iwo Jima, the Marines were detailed to Hill 55 near Da Nang. Hanks described his time as “weeks and weeks of nothing interspersed with seconds of sheer terror.”

His three buddies were machine gunners. He was a bazooka man nicknamed, naturally, “Rockets.”

Months later, DeVenezia and Puleo were transferred to other rifle companies, then Falk went off elsewhere. Finally, Hanks was transferred to flame throwers, which he never used in battle.

The deadly chaos of Vietnam became evident early on.

“The villages we protected during the day would come out and kill us,” DeVenezia said. “My only thought was I’m going to kill 1,000 of them before they kill me.”

He was certain he was a dead man. It was only a matter of time. Indeed, he did get shot, as did Puleo.

In fact, Hanks said Puleo was nearly killed when his unit was overrun. He played dead as enemy soldiers finished off the wounded. He spent a year in and out of hospitals after Vietnam and became successful in sales, although Puleo once told a magazine he could become unpredictable and volatile. In recent years, he has become a Christian speaker.

DeVenezia recounted a story not uncommon with Vietnam vets, “I still have a lot of anger and bitterness. Coming home, I was timid and withdrawn. I didn’t want to talk about it because you’d get into arguments. I didn’t want to deal with that.”

In the 1970s, he went to the VA and said he suffered from PTSD. “But they didn’t recognize it. It took 27 or 28 years to get a disability rating.”

DeVenezia ran a construction firm building churches, schools and small factories.

Falk spent a career as a manager for Walmart.

Hanks came home, went to college, grew his hair long, bought a cheap van and drove to San Francisco where he partied, trying to forget the war he came to oppose.

Later, he moved to the Atlanta area and joined up with Lehman Brothers. He has two grown children and a grandson. He got a VA disability after contracting prostate cancer, which may have been caused by Agent Orange. Still, he has the shoulders of a weight-lifter (which he is) and the legs of a long-distance bicyclist.

The four reacquainted about five years ago through the Internet, though they have different versions of how it happened. Some have met up since then, although not all four at once — until Saturday where they will again stand on a beach with a surfboard, remembering when.