Robert Ballard discovered the Titanic in 1985 as part of a top-secret US Navy mission

The real story of how explorer Robert Ballard discovered the Titanic shipwreck remained a top-secret within the US government until only recently.

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CBS News reports on the exhibit ‘Titanic: The Untold Story’ that is on display at the National Geographic Museum. The exhibit details the remarkable story of how the US Navy used the search for the ill-fated luxury liner as a cover-up story.

In 1985, explorer Robert Ballard was keen to find the sunken Titanic but was having trouble securing funds for the project. Having been a naval commander during the Cold War, Ballard approached the US Navy and its Deputy Chief of Naval Operations Ronald Thunman for help.

Thunman recalled: "He [Ballard] said, 'All my life I've wanted to go find the Titanic.' And I was taken aback by that.”

"I said, 'Come on, this is a serious, top secret operation. Find the Titanic? That's crazy!'"

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Thunman agreed to help fund Ballard’s exploration, but only if Ballard would assist the US Navy in locating two missing nuclear submarines, the Thresher and the Scorpion, which had both sunk in the Atlantic in the 1960s.

Ballard said that the US Navy didn’t want anyone else finding the sunken submarines, particularly the Russians.

"It was very top secret," Ballard said. "And so I said, 'Well, let's tell the world I am going after the Titanic.'"

"So, it was a deal – you'll let me do what I want to do, if I do what you want to do," Ballard said.

Ballard was successful in finding the Scorpion before turning his attention the Titanic. He was nearing the end of his mission and only had 12 days left to find the luxury liner, but was able to locate the famed shipwreck in just eight days.

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Though finding the Titanic was a dream come true for Ballard, the actual moment he and his crew saw the ship was somber.

"We realized we were dancing on someone's grave, and we were embarrassed,” said Ballard.

“The mood, it was like someone took a wall switch and went click. And we became sober, calm, respectful, and we made a promise to never take anything from that ship, and to treat it with great respect."

"You don't go to Gettysburg with a shovel. You don't take belt buckles off the Arizona," he replied.

Watch the CBS News report on the exhibition here:

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The hunt for the Titanic shipwreck was a cover-up by the US Navy