I can't remember the name of it but the premise is this:
Two portals open on a typical fantasy world. A large stockpile of modern military weaponry and instructions to use it fall into the evil kingdom. A US Marines Drill Instructor (or maybe Gunnery Sergeant) falls through to the good kingdom. He proceed to train them in geurilla tactics to overthrow the evil empire.
Any help would be greatly appreciated.
I think it found it by perusing a forum thread asking for recommendations of books/stories about Modern Soldiers in Fantasy Settings.
Appears to be the DemonTech Series by David Sherman.
The Evil guys do a summoning that gives them tech manuals for weapons and tactics I believe.
The good guys try to imitate it, but the demons which they use are confused so they instead send the good guys a Marine Gunnery Sgt. He goes on to train their Marines. Lord Gunny indeed.
There are four books:
Onslaught (2002)
The diabolic armies appear invincible– but they haven’t met the Marines.
The Dark Prince’s power to summon demons has made his forces second to none, and ensured his place as one of the invasion’s leaders. Not content to merely seize his father’s throne, the renegade royal dreams of world conquest–and with his army and his black arts, there is little to stop him.
So unexpected, so well planned is the invasion of the free port New Bally that out of hundreds in the city, only two escape capture. Haft and Spinner will need all their courage and cunning to retrieve their weapons from their enemy-held ship, cross the open meadows surrounding the city walls, and escape into the forest beyond–where they hope to regroup and drive back the invaders. Luckily, Haft and Spinner are no ordinary men. They are Marines . . .
...
Rally Point (2003)
Ruthless and seemingly indestructible, the dark army didn’t count on the few, the proud, the Marines.
The Dark Prince’s vast armies have destroyed nation after nation with the aid of powerful demon magic. Their total victory would be swift and certain except for two things: Haft and Spinner, a pair of soldiers trained in the art of warfare through the teachings of a magically transported Marine Gunnery Sergeant.
The Dark Prince’s orders are swift and simple: find them. Haft and Spinner, along with scores of soldiers and refugees, are determined to form an army and defeat the invaders. Outnumbered and outgunned, they must uncover and kill the enemy before the enemy kills them. Haft and Spinner have already accomplished great feats. But to achieve the impossible will require a few strokes of genius and a few good men. Fortunately, these Marines have both. . . .
...
Gulf Run (2003)
Only a miracle can save them now. Luckily, they have one: the Marines.
Like an invincible tidal wave of evil, the Dark Prince’s conquering armies roar across the land, leaving death and destruction in their wake. So far Marines Haft and Spinner have managed to stay one step ahead of the invaders, picking up hundreds of refugees and soldiers as they struggle to reach their salvation at the edge of the sea. Against all odds, they’ve even managed to inflict some damage on the vastly superior forces.
Yet for every enemy soldier killed, ten more appear in his place, and the Dark Prince’s demon magic ensures their weapons are brutally effective. The outlook is not promising for the ragged band of rebels, pursued by bloodthirsty troops, hounded by bandits, and forced across a desert where death awaits all trespassers. As the noose tightens and the Dark Prince prepares the final coup de grace, it may look like Haft and Spinner and their embattled crew are finished. But these Marines have only just begun to fight.
...
Get Her Back! (2010)
Send in the Marines! Because the Golden Girl is on the loose...
And it's up to Haft and the Bloody Axes to...Get Her Back!
When headstrong Alyine sets off on her own to find her left-behind musician, life gets interesting for those who must go after her. Angry nomads, great hunting cats, and desert death-matches stand between the Golden Girl and her rescuers. Using every trick at their disposal, Haft and his men are more than up to the challenge!
Have no doubt, they'll get their Girl!
Grunts! by Mary Gentle could be it.
from a review:
Just as in every military campaign, in the Final Battle between the Dark and the Light, it's the ordinary soldiers who get the short end of the stick. On the Dark side, that means the orcs. Ashnak is a minion of the nameless necromancer, who in turn is lackey to the Dark Lord. When he and his orcs are sent on a secret mission in preparation for the Final Battle, he has no idea that it will turn his life and the lives of hundreds of orcs in an entirely new direction.
The nameless necromancer instructs Ashnak and Co. to act as a protective guard to Ned and Will Brandiman, two extremely nasty and murderous halfling thieves sent by the Dark Lord to steal special weapons from a dragon's hoard. But the dragon, Dagurashibanipal, has cursed the hoard with the following curse: What you steal, you shall become. Now, it just so happens that the dragon has accumulated some of its booty from other worlds... including ours. And what they steal from the dragon happens to be weaponry and uniforms courtesy of the United States Marine Corps. So the effect of the curse is to transform the orcs into MARINES, in all of their disciplined, well-trained glory. Or at least as disciplined and well-trained as bloodthirsty wild creatures can be...
