Stationed on the New Guinea coast during World War II, Ed Downey tried to maneuver a Jeep out of a muddy field and was shocked to hear a dog’s whimper coming from a nearby foxhole. Wading through tall weeds on that March day in 1944, he sensed movement.

“A pair of dark eyes, glinting in the dull light, gazed up at him, imploringly. They seemed disproportionately large for the sodden floor-mop of hair they seemed to inhabit,” writes Damien Lewis in the book, “Smoky The Brave: How a Feisty Yorkshire Terrier Mascot Became a Comrade-in-Arms during World War II” (Da Capo), out Tuesday.

Downey, not a dog lover, gave the pup to another squad member, who passed it along to Downey’s tentmate, Bill Wynne. Wynne was immediately taken with the adorable pooch — named Smokums by another squad member due to her “smoky grey-blue coloring.”

“She was so small, it was almost unreal. When standing, she came no higher than Wynne’s boot tops,” writes Lewis.

“It was the eyes that struck [Wynne] most powerfully. A deep amber-brown, they had a fierce sparkle in them that spoke of an innate loyalty and a quick-witted intelligence.”

Wynne, who had learned to train dogs back home in Cleveland, shortened her name to Smoky and started teaching her tricks. He began with simple commands like “Sit!” “Stay!” and “Heel!” and evolved to “Bang!” where Wynne brandished finger guns and Smoky played dead.

Smoky had a significant impact on Wynne and his fellow members of the 26th Photo Reconnaissance Squadron. Stationed in the Pacific, their only entertainment was radio broadcasts by Tokyo Rose, who seduced listeners while spreading anti-American propaganda.

To blow off steam, the squad played softball on a bulldozed strip of land. Smoky attended the games, “chasing every ball that came in her direction.”

During one game, Smoky chased a hard-hit ground ball to third base “like a bullet from a gun.”

“The player on third base bent to scoop up the ball, just as a careening canine hairball overtook it,” Lewis writes. “Smoky leapt to seize the ball and was flipped head over heels by the fast-spinning projectile, landing in the startled baseman’s glove.” The players on both sides could barely contain their laughter.

When the military publication Yank magazine announced a contest for best mascot, Wynne was excited to enter Smoky.

He photographed the dog lounging inside his helmet, a perfect fit.

But, to win, he thought of an even bigger idea.

Wynne designed a tiny parachute harness for Smoky. One soldier climbed a tree high enough to drop her, while two others held a blanket below to catch her and a fourth worked the camera.

On Wynne’s signal, Smoky and her parachute were dropped from a high branch. The dog floated toward the ground, “her four legs splayed wide as if ready for a proper landing,” and she dropped into the center of the blanket, leading to loud cheers from the squad.

Smoky performed this “jump” four more times, but on her sixth jump, a fierce gust of wind collapsed the chute and Smoky was slammed hard to the ground, far off from the waiting blanket.

“She bounced on impact, yelping with pain as she turned a somersault in the air, her head bent at an odd angle,” Lewis writes. “Moments later she hit the ground again and lay still.”

Wynne, “consumed with fear,” rushed to care for his companion.

Smoky was better by morning, but Wynne was furious with himself for placing his beloved dog at risk. He scrapped the parachute photos and used the picture of Smoky resting in his helmet for the contest entry instead.

Shortly after, Wynne developed a 105-degree fever and was rushed to a nearby tent hospital, where doctors concluded he likely had dengue fever.

On his third day in the hospital, two members of the squad brought him his mail and his dog. Smoky was overjoyed, running furiously around the tent and yelping excitedly. Wynne finally got the pup to settle on his bed, and then opened his mail, which included a letter from Yank magazine informing him that Smoky had won the contest.

Word spread throughout the hospital, and the nurses, noting the joyous reaction, asked Wynne if they could bring Smoky to visit patients, an unusual request for the time.

“As soon as Smoky made an appearance, the eyes of the war-wounded were drawn towards [the] dog,” Lewis writes. “Their vacant, thousand-yard stares seemed to soften slightly, regaining their spark and focus whenever she was within their sight.” (In 2014, the television show “Animal Planet” declared that Smoky’s visit to the tent hospital made her the world’s first-ever therapy dog of record.)

Smoky won a mascot award from Yank magazine for an adorable pic Wynne took of the dog in his helmet.

Smoky continued visiting patients until Wynne was released a few days later.

In January 1945, the 26th was reassigned to the Philippines, where fighting against the Japanese had been brutal.

The following month, they faced a potentially devastating dilemma. Their mission depended on their ability to transmit coded messages, disseminating the enemy intelligence they gathered to commanders in the field.

Heavy fighting had damaged the squad’s communications center. To repair it, a wire would need to be fed through a 70-foot-long, 8-inch-in-diameter underground culvert beneath a crucial taxiway. Digging up the taxiway would take three days and make dozens of their men sitting ducks for enemy bombers, in addition to hampering air operations.

There was only one option for solving the problem that didn’t risk human lives: sending Smoky through the culvert with the wire attached to her. This method would take just several minutes and keep everyone in the 26th safe. Smoky, however, would be very much at risk.

Wynne agreed on the conditions that all air activity above them cease while Smoky was underground and that if Smoky became stuck, they would dig her out from directly above her location in the culvert.

He checked out the three drainage pipes under the taxiway. Two were fully clogged, but one had about 4 inches of visible space that Smoky could fit through. They chose that pipe for the mission.

One end of the wire was attached to Smoky’s collar. Wynne placed Smoky at the opening of the pipe and raced to the other end. He laid on the ground, put his face next to the pipe and yelled, “Come, Smoky, come!”

After a brief hesitation, Smoky made her way into the pipe, her tiny paws scraping the bottom as a commander unfurled the wire. But about halfway through, her pull on the wire stopped. The wire was stuck, and as Smoky struggled to free herself, she kicked up a storm of dust. Now, no one could even see the dog in the pipe.

Smoky and his award.

After a few tense seconds, though, the wire was freed, and Smoky ran scrambling out into Wynne’s arms.

Mission accomplished.

Wynne left for home in August 1945 as the war came to an end. Returning soldiers were ordered to leave all pets behind, but he smuggled Smoky aboard the ship home in an oxygen mask.

After the war, Wynne and Smoky performed their tricks locally, including for injured veterans in Cleveland war hospitals.

Wynne worked as a flight photographer until 1953, when he joined the photo desk of the Cleveland Plain Dealer newspaper. The following year, he retired his beloved pet from performing.

When Smoky died on Feb. 21, 1957, the Plain Dealer ran an obituary outlining her achievements. The day the article ran, Wynne’s wife, Margie, took a phone call from a local woman named Grace Guderian, who had worked as a nurse at a field hospital during the war.

Guderian explained to Margie that “she had lost a female [Yorkshire terrier] in New Guinea in early 1944.”

Her fiancée had bought the dog for her in Brisbane, and she had named it Christmas. At the time, Smoky was likely the only Yorkshire Terrier in all of New Guinea, Lewis says. The two women quickly discerned that Christmas was Smoky.

Still, Christmas was lost 180 miles from where Smoky had been found. How did she get from the first locale to the second?

It turned out that the day Christmas went missing, Guderian had gone to a show on her base starring comedy legend Bob Hope, who performed regularly for US soldiers overseas during the war.

After the show, Hope traveled on to other bases, including near where Wynne was stationed. While there were frequent flights between bases, it seemed likely that the world’s most incredible Yorkshire terrier had hitched a ride with one of the world’s most popular entertainers.