Editor's Note: Twenty years ago, James Cameron's blockbuster film "Titanic" entranced audiences around the globe. But it was less than 10 years ago that Robert Ballard, the oceanographer who discovered the Titanic in 1985, revealed to the world that he found the famous shipwreck as the result of a top-secret military expedition. Here's how National Geographic broke the news on June 2, 2008.
The 1985 discovery of the Titanic stemmed from a secret United States Navy investigation of two wrecked nuclear submarines, according to the oceanographer who found the infamous ocean liner.
Pieces of this Cold War tale have been known since the mid-1990s, but more complete details are now coming to light, said Titanic's discoverer, Robert Ballard.
"The Navy is finally discussing it," said Ballard, an oceanographer at the University of Rhode Island in Narragansett and the Mystic Aquarium and Institute for Exploration in Connecticut.
Ballard met with the Navy in 1982 to request funding to develop the robotic submersible technology he needed to find the Titanic.
Ballard is also a National Geographic Society explorer-in-residence. (National Geographic News is owned by the National Geographic Society.)
Ronald Thunman, then the deputy chief of naval operations for submarine warfare, told Ballard the military was interested in the technology—but for the purpose of investigating the wreckage of the U.S.S.Thresher and U.S.S. Scorpion.
Since Ballard's technology would be able to reach the sunken subs and take pictures, the oceanographer agreed to help out.
He then asked the Navy if he could search for the Titanic, which was located between the two wrecks.
"I was a little short with him," said Thunman, who retired as a vice admiral and now lives in Springfield, Illinois. He emphasized that the mission was to study the sunken warships.
Once Ballard had completed his mission—if time was left—Thunman said, Ballard could do what he wanted, but never gave him explicit permission to search for the Titanic.
Ballard said Navy Secretary John Lehman knew of the plan.
"But the Navy never expected me to find the Titanic, and so when that happened, they got really nervous because of the publicity," Ballard said.
"But people were so focused on the legend of the Titanic they never connected the dots."
The Thresher and Scorpion had sunk in the North Atlantic Ocean at depths of between 10,000 and 15,000 feet (3,000 and 4,600 meters).
The military wanted to know the fate of the nuclear reactors that powered the ships, Ballard said.
This knowledge was to help determine the environmental safety of disposing of additional nuclear materials in the oceans.
The Navy also wanted to find out if there was any evidence to support the theory that the Scorpion had been shot down by the Soviets.
Ballard's data showed that the nuclear reactors were safe on the ocean bottom and were having no impact on the environment, according to Thunman.
The data also confirmed that Thresher likely had sunk after a piping failure led to a nuclear power collapse, he added. Details surrounding the Scorpion are less certain.
A catastrophic mishap of some sort led to a flooding of the forward end of the submarine, Thunman said. The rear end remained sealed and imploded once the sub sank beneath a certain depth.
"We saw no indication of some sort of external weapon that caused the ship to go down," Thunman said—dismissing the theory that the Russians torpedoed the submarine in retaliation for spying.
While searching for the sunken submarines, Ballard learned an invaluable lesson on the effects of ocean currents on sinking debris: The heaviest stuff sinks quickly.
The result is a debris trail laid out according to the physics of the currents.
With just 12 days left over in his mission, Ballard began searching for the Titanic, using this information to track down the ocean liner. He speculated that the ship had broken in half and left a debris trail as it sank.
"That's what saved our butts," Ballard said. "It turned out to be true."
The explorer has since used a similar technique to find other sunken ships and treasures, including his expeditions to the Black Sea.
Are these expeditions also part of top-secret missions? After all, the Black Sea is in the volatile Middle East.
"The Cold War is over," Ballard said. "I'm no longer in the Navy."
Watch National Geographic's one-hour documentary marking the 20th anniversary of the hit film "Titanic" on Sunday, November 26 at 9/8c on the National Geographic Channel.