As photographer Joe Rosenthal stood on Mount Suribachi that day, aimed his Speed Graphic at the American flag and froze a moment in history, Marine Corps Sgt. Bill Genaust’s movie camera was already rolling.

Genaust filmed the Marines readying the long pipe to which the flag was attached. He caught them jamming the pipe into the ground. And he filmed the three seconds it took to raise it during the World War II battle of Iwo Jima.

He showed the flag caught in the wind. He showed the Marines piling rocks at the base of the pipe so it would stay up. He showed the grit and reality of the event.

Genaust’s clip also proved to doubters that Rosenthal’s Feb. 23, 1945, picture was not set up. Copies helped the Marines ascertain the identities of the men in the photograph.

But Genaust’s original “in camera” color film has been lost.

This copy of Marine Sgt. Bill Genaust’s footage shows the flags on Mount Suribachi during the World War II battle of Iwo Jima on Feb. 23, 1945. (National Archives)

Seventy-five years later, all that survive are copies, according to the National Archives. The earliest one dates to 1951, six years after the battle, said Criss Austin, the Archives’ supervisory motion picture preservation specialist.

“We like to have the original because that is the authentic record of what happened,” said Austin, who wrote a chapter for the book “Investigating Iwo,” published last year by the Marine Corps History Division.

It can be crucial evidence.

“Any time you make a copy of a film … you lose about 15 percent of the resolution,” she said in an interview. “You’re losing definition. It’s not as crisp.”

How the original vanished remains a mystery.

The story of the Iwo Jima flag-raising, and the historic photo and motion picture film that resulted, have been marked by confusion since the beginning.

There were actually two flag-raisings on Mount Suribachi that Friday.

The first flag raised was deemed too small and was soon replaced by a larger flag. The raising of the second one was captured by Rosenthal, an Associated Press photographer, and became famous. (Both flags are on display at the National Museum of the Marine Corps, in Triangle, Va.)

Further confusion came when officials tried to identify the Marines in the Rosenthal picture, most of whom have their backs to the camera. Three times, the identifications have been changed — the latest as recently as October.

After new investigation, the Marines said Cpl. Harold “Pie” Keller was in the picture, and Pfc. Rene Gagnon was not.

Four years ago, the Marines made another correction, saying Pvt. Harold H. Schultz was in the photo, and Navy Pharmacist’s Mate 2nd Class John Bradley was not.

In 1947, the Marines said Cpl. Harlon Block was in the picture, and Sgt. Henry Hansen was not.

Genaust’s film has been another mystery. He captured the first flag after it had been raised and filmed the second as it was going up.

A Marine Corps cameraman, 38-year-old Genaust, of Sioux Falls, S.D., had already been wounded in action on Saipan and had been filming the Iwo Jima battle since its start on Feb. 19.

The in-camera roll of film appears to have gotten lost in a trans-ocean, cross-country bureaucratic and technical mix-up, Austin wrote.

Genaust shot his moving pictures on 16mm color film with a Bell & Howell camera, according to Austin.

In addition to the flag-raising, he filmed the grisly combat on the island — U.S. ships and artillery blasting Japanese positions, Marines throwing explosive charges into caves, and a blasted landscape littered with dead bodies.

Nine days after the battle began, Lt. Herbert B. Schlosberg, a Marine photographic officer, was ordered to take the footage shot by Genaust and others from Iwo Jima to the Navy Photographic Science Laboratory, at what is now Joint Base Anacostia-Bolling in Washington, to be developed, Austin wrote.

There, the footage could be edited, cut and spliced for multiple purposes.

Genaust’s film arrived, Austin said, and the footage of the flags was spliced together — but in the wrong order.

The first 35 seconds show the second flag-raising scene. The last 19 seconds show the first flag after it had been raised.

“The lab personnel in 1945 would have had no way of knowing in what order the footage occurred without the direct input of the cameraman or his superiors,” Austin wrote.

But Genaust was killed in action two weeks later.

The Anacostia lab was the last place the original was seen, Austin said.

Meanwhile, copies of the footage have been extensively used and reprinted over the years for its graphic depiction of the battle in which about 6,800 Americans and 20,000 Japanese were killed.

In 2016, a fresh Marine Corps review of the flag-raising images got underway, and television filmmakers asked the Archives for high-resolution digital scans of Genaust’s footage.

The Archives set out to find the original. Twelve versions of the footage were located and sent to Austin’s lab to determine which one had been in Genaust’s camera, she wrote.

She analyzed them all.

None had the special “edge code” on the film strip that would have indicated the original.

With a feeling of “sinking dread,” she realized the Archives didn’t have it. “I was like, ‘Oh, no. We don’t have the original.’ ”

The earliest copy dated only to 1951, she said.

“The whereabouts of Genaust’s original camera footage is still a mystery,” she wrote. It “may be lost entirely, it may still be in another repository, or it may be hidden in one of the many locations it traveled to in the course of its multiple uses.”

Lost, too, is the cameraman who shot the film.

Genaust’s body was never recovered and is probably still somewhere on Iwo Jima.

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