Beneath the trenches: The secret world of the Great War revealed

Power Players

Power Players

Beneath the long-abandoned battlefields of World War I, in the idyllic French countryside, lies a hidden underground world where soldiers sought nighttime refuge from long days spent in the trenches above.

These subterranean cities, a secret to the world until now, have been captured in stunning detail by American photographer Jeffrey Gusky, who was granted near-exclusive access to photograph the hidden spaces by the French locals who have protected them for generations.

On this Veteran’s Day, Gusky told “Power Players” about the remnants of tragedy and treasure he found inside the cavernous dwellings.

“Modern underground cities beneath the trenches, loaded with art, loaded with the infrastructure of modern cities, tens of thousands of men occupying these places at any given time throughout the war,” Gusky told “Power Players.”

“Very often stairways went directly to the trenches, and then they would descend back into safety,” Gusky said. “And there was one place where Americans were where [it] actually wasn't a stairway, it was a slide, and you'd come in and you see not ‘Welcome In,’ but ‘Hell, Come In.’”

The underground network of cities, which extended 18 miles long in one place, was constructed from ancient stone quarries that had once been hollowed out to build castles and cathedrals.

It was with the stone that soldiers found a means of self-expression, from sketching messages to loved ones to carving complex masterpieces of art. “You see their soul in the art, in the inscriptions,” said Gusky.

“They walked into a situation that no one could have imagined, and what we see underground is how they, when faced with the inhuman scale of modern life, where the meaning of life had vanished, they hold onto their humanity,” he said.

Thousands of American soldiers were among those who passed through the tunnels during the war, and they left a distinctive mark.

“They were the most prolific Army of any of the armies in the short time they were there,” Gusky said. “They loved their country, they knew who they were, they knew what they were fighting for, and you can feel it in their walls.”

To see Gusky’s photographs for yourself, and hear about some of the pieces of art that most affected him, check out this episode of “Power Players.”

ABC News’ Angel Canales, Ali Dukakis, and Gary Westphalen contributed to this episode.