This is probably David Weber's "Sword Brother" (2007). The wizard Wencit of Rûm needs to find help before Bahzell heads into a trap and ends up with a US Marines LAV. They fight 5 dragon-like demons before being sent home.
Gunnery Sargent Ken Houghton and PFC Jack Mashita are in a Marine LAV:
The thought ran below the surface of his mind as he stood in the commander's hatch on the right side of the LAV's flat-topped turret and gazed out into the night. As the senior noncom in Lieutenant Alvarez' platoon, Houghton commanded the number two LAV (unofficially known as "Tough Mama" by her crew), with PFC Jack Mashita as his driver and Corporal Diego Santander as his gunner. Tough Mama was technically an LAV-25, a Light Armored Vehicle based on the Canadian-built MOWAG Piranha, an eight-wheel amphibious vehicle, armored against small arms fire and armed with an M242 25-millimeter Bushmaster chain gun and a coaxial M240 7.62-millimeter machine gun.
That gets grabbed from the Middle East (exact location unspecified):
And then, as suddenly as the universe's colors had disappeared, they were back.
But they were the wrong colors.
The tans and grays and sun-blasted browns of the Middle East were gone. And so was the night. The LAV sat on a gently sloping hillside covered in prairie grasses three or four feet tall under a sun that was still at least two or three hours short of setting.
Wencit shows (not mind-to-mind, but like a magical TV) Houghton a summary of the fight against Carnadosa:
The Marine's mouth snapped shut again as the ripple effect cleared as suddenly as it had appeared. In its place were images—sharp, as crystal-clear as any video screen or television Houghton had ever seen. And, as he saw them, Houghton felt a sudden, total confidence that what he was seeing was an actual, faithful record of what had truly happened.
It was one of the most horrific things he had ever seen.
[...]
He stared at Wencit's images and saw brutal combat with swords, axes, pikes and halberds—[...] And he saw other flames—the flames of burning cities and villages, their streets littered with the bodies of those who had once lived in those blazing homes. [...] He saw blood soaked altars, surrounded by the butchered bodies of sacrificial victims while still more victims were dragged, fighting frantically, to their fates. And he saw... creatures he had no names for—creatures out of the darkest depths of nightmare—killing and maiming, devouring. He saw them being directed, controlled, in their slaughter.
And he saw the men—and women—who stood against the tide of butchery and darkness. He watched them, recognized the iron determination and raw courage which kept them on their feet, facing that avalanche of horror when simple sanity must have cried out for them to flee for their lives. Some of them seemed wrapped in glittering coronas of blue light, like some sort of lightning. Others were simply men and women, with no light, no special aura. Only men and women who could not let the darkness triumph unopposed. Who had to face it.
And who died fighting it.
He saw it all, and only much later did he realize that what seemed to have taken hours at the time could not have lasted more than a very few minutes.
The demons they're fighting aren't really dragons, but they have wings and claws:
The night suddenly shattered as something even darker and blacker than it was, and almost as enormous, exploded from the tunnel mouth. Bahzell's mind insisted that it couldn't possibly have squeezed itself into an opening that small as huge, segmented spider-like legs—blacker than black, yet glaring with sick green light for eyes that could see—and ribbed, bat-like wings unfolded themselves. A head that belonged on something from night-black depths where sunlight never shone opened its mouth to bare curving fangs half as long as Bahzell, and the demon shrieked its fury as it launched itself down the hillside towards them with all the impossible quickness of its hell-born kind.
