You can’t miss it. Walk into the exhibit room at the Historical Society of Cheshire County in Keene and it commands its environs, floor to ceiling — a Sherman tank — complete with turret, cannon and camouflage netting on top.

But looks are deceptive, and deception is the theme in this fascinating summer-long exhibit about a classified Army unit that played a vital role for the U.S. at the end of World War II.

Filled with air, the tank is a 98-pound, Army-green rubber blob with painted black markings to make it look like the real thing. Pull the plug and it would collapse around you, which happened to an unsuspecting general when a “tank” folded on him during World War II. Fake tanks were part of the Ghost Army’s repertoire, along with a host of other props intended to deceive the Germans.

For nearly three-quarters of a century, the 23rd Headquarters Special Troops — the Ghost Army — was little more than an apparition. Its mission and men were sworn to secrecy, even silencing gregarious personalities like the late Mickey McKane of Marlborough and Keene. McKane is prominently featured in the exhibit; many artworks and stories come courtesy of Keith McKane of Keene, the youngest of Mickey McKane’s three sons. They include stories about famous fashion designer Bill Blass, who was Mickey McKane’s best friend and best man at his wedding in Keene.

The top-secret unit, activated on Jan. 20, 1944, was created to fool the enemy, not fight it. The 1,105 men, including 82 officers, were illusionists as much as they were soldiers, stealthily crossing the countrysides of France, Belgium, Luxembourg and Germany in trying to lure the enemy away from real battles planned elsewhere.

U.S. Rep. Annie Kuster, D-N.H., who visited the exhibit Friday, said she has a special interest in the Ghost Army, as she’s enamored with World War II history.

Her father, Malcolm McLane, was a pilot who was in the air during the invasion of Normandy on D-Day. Six months later, on Christmas Eve, McLane was shot down during the Battle of the Bulge and taken to a Nazi prisoner-of-war camp. He survived the experience and later was elected mayor of Concord. After reading about the Ghost Army, Kuster said she believes it was never given its proper due.

Thus, in February, Kuster co-sponsored the Ghost Army Congressional Gold Medal Act with Rep. Chris Stewart, R-Utah, to honor those who served in the unit. It passed the U.S. House May 18, and Kuster said she’s hopeful the bipartisan measure will make it through the Senate, where it also needs a two-thirds majority vote.

“This is just an incredible story. … And it really worked to deceive the Germans,” Kuster said. “They helped us win the war, but afterward they were sworn to secrecy.”

No one knew that for half a century. The Ghost Army’s existence remained classified until the mid-1990s, and only in the past 10 years have details slowly emerged. Filmmaker Rick Beyer produced “The Ghost Army” for PBS in 2013, interviewing 19 members who were still alive, and in 2015 he co-authored a book with Elizabeth Sayles, “The Ghost Army of World War II: How One Top-Secret Unit Deceived the Enemy.”

Beyer, who was a classmate of Kuster’s at Dartmouth College in the late 1970s, is behind the national exhibit that’s on display at the historical society in Keene through Sept. 2. Called the Ghost Army Legacy Project, it features wall-boards that circle the room detailing the Ghost Army’s objectives, missions and personal stories of some of its members. It includes photos and sketch artifacts drawn by the soldiers themselves.

One entire wall is dedicated to Mickey McKane, an artist, musician and performer, who had appeared in John Barrymore’s Oscar-nominated “Reunion in Vienna.” Mickey McKane was attending the Pratt Institute of Fine Arts in Brooklyn, N.Y., when the Army recruited him. Though he died in 1990, his three sons have shared many of his stories.

Keith McKane and his wife, Tammy, were at Friday’s informal gathering with Kuster at the historical society. Keith and his brother Morgan McKane talked at length about their father in a May 11, 2013, Sentinel article, and on Friday Keith said he was overwhelmed to see his father so prominently displayed in the exhibit.

“This means so much,” he said. “I’m so quick to remind people how much they gave, not to brag about my father. They were heroes. And to not know if what they did worked …”

For example, in Operation Viersen, the Ghost Army wanted the Germans to think the Allies would be crossing the Rhine River 15 miles north of where they actually intended to attack. They faked the buildup of two divisions (about 30,000 men) with their traveling props, and even had the Germans believing the attack would be delayed. The Ghost Army was long gone when the Germans came ready for battle; the real crossing resulted in light resistance and only 31 Allied casualties. Overall, officials have said the Ghost Army may have saved more than 30,000 Allied lives in the war.

Part of the deception was carrying on misleading conversations for the Germans to overhear. Keith McKane said their clandestine operations even led to a friendly fire fistfight. Seems that the Ghost Army was called upon for assistance by another unit that had no idea it was forbidden to engage the enemy. When members of the two units later crossed paths, it led to a fight, McKane said.

McKane wasn’t the only local son of a Ghost Army member at Friday’s gathering. Timothy H. Congdon of Keene said his father, Richard H. Congdon, was also in the Ghost Army. However, Tim Congdon said his father never talked about it and died before it was declassified.

Historical Society Executive Director Alan Rumrill said McKane’s involvement played a role in the exhibit coming to Keene. It had been in North Carolina and will move to Chicago after its run here. The historical society first showed Beyer’s film three years ago, and that sparked further interest. Rumrill said it has attracted a lot of traffic since it opened June 2.

“People are surprised and pleased that they can learn about it,” he said. “It’s been really fantastic.”