A memorial that honors those killed in the HMT Rohna attack is on display at the Fort Mitchell National Cemetery in Seale, Alabama. The incident remained classified for years.

BEND — Four men from Oregon were killed during World War II in one of the deadliest attacks at sea in U.S. history, and their families may have never known the whole story.

The HMT Rohna, a British transport ship carrying American soldiers, was hit on Thanksgiving Day 1943 by a German missile off the coast of North Africa. It was the first radio-guided missile ever used against the U.S., killing 1,015 American troops, including the four men from Oregon.

The 966 survivors were ordered to remain silent or face court-martial, and the incident remained classified long after the war, according to Jack Ballo, a New Jersey-based filmmaker who is documenting the secrecy around the attack for his film, “Rohna: Classified.”

On Memorial Day, as families remember their loved ones killed serving in the U.S. military, Ballo is searching for relatives of the soldiers killed on the HMT Rohna. He hopes to possibly offer some closure.

Most of the living relatives are either second- or third-generation descendants of the soldiers and likely have no idea how they were killed, Ballo said.

“These families, they don’t know what happened,” he said. “They don’t know how their great-uncle died in this historic attack.”

Ballo also wants to learn more about the soldiers. He only has brief descriptions from military records. He has the name and city or county of the Oregon soldiers, but no other details.

The four Oregon soldiers were: Elmer J. Laine, of Astoria; Norman J. Gillespie, of Aumsville; James R. Webb, of Umatilla County; and Warren B. Perkins, of Multnomah County.

Their parents were never told what happened, Ballo said. The attack was classified so the Germans wouldn’t know how successful it was, but the censorship was painful for the families, he said.

The Oregon soldiers and other troops sent Christmas cards home before they boarded the ship. All the families received the cards and assumed everything was fine, but by that time the troops were already dead, Ballo said.

“One of the driving forces of making this film is understanding what these families went through,” he said.

Two months after the attack, families started to receive telegrams that said their sons were missing in action. Five months later, they received reports that their sons were presumed dead. No other details were given, other than they died in a ship sunk in combat, Ballo said.

“Just imagine your son goes to war and you get a card in the mail telling you he died,” Ballo said. “No body. No funeral. No closure.”

It wasn’t until 50 years later that details of the attack became widely known.

A group of survivors met for a reunion in 1993 and that resulted in more public attention. The survivors then created a memorial and spoke more openly about their experience.

“Survivors didn’t tell their families,” Ballo said. “That’s why the story never really got any traction. It took 50 years before these survivors got together again and that’s when they started talking.”

Still, the attack is a little-known piece of World War II history Ballo is trying to highlight in his film.

“It was a long time ago,” Ballo said. “That’s why I consider this film a last chance to tell this story.”