The Lost Regiment

The Lost Regiment is a series of science fiction novels by William Fortschen. After the Battle of Gettysburg, the 35th Maine volunteer regiment is swept into a portal and lands on an alien world. The good news for them is that there are other humans on the planet - Russians, Romans, Carthaginians, Japanese, Chinese, and others - who entered the same way the 35th Maine did. The bad news is that they share the planet with The Hordes - a race of 9-foot tall aliens based on the Mongol horde who demand a tithe of humans every twenty years or thereabouts to eat. The series follows the men of the 35th, as they try to use their superior technology to unite the humans against the Horde while forging a democratic republic like the one they left behind.

The series consists of eight books, with a ninth one that takes place after a Time Skip: 1. Rally Cry (1990) 2. Union Forever (1991) 3. Terrible Swift Sword (1992) 4. Fateful Lightning (1992) 5. Battle Hymn (1997) 6. Never Sound Retreat (1998) 7. A Band of Brothers (1999) 8. Men of War (1999) 9. Down to the Sea (2000)

The series contains the following tropes:

 * Alien Sky: Two moons and a galaxy are visible on Valennia.
 * The Alliance: The Union, consisting of the 35th Maine, Rus, Roum, Cartha, Chin, Nippon, and others.
 * American Civil War
 * Badass Bookworm: Andrew Lawrence Keane.
 * Break the Cutie: Vincent Hawthorne.
 * Character Development
 * Complete Monster: Tamuka, who wishes to exterminate humanity.
 * Deus Ex Machina:
 * Every Land Ironclad is a Pinto
 * Face Heel Turn:
 * Fantasy Counterpart Culture: The Horde for the Mongols.
 * And the Merki are named after the Merkits, a rival tribe of the Mongols.
 * Foe Yay: Most villains tend to have this with at least one of the heroes.
 * Giving Radio to the Romans: Done by the lost regiment
 * Good Republic, Evil Empire
 * Great Escape: The whole plot of Battle Hymn
 * Heel Face Turn:
 * Heroic Sacrifice: Way too many to count.
 * The Horde: the main antagonists. Essentially the Mongol Horde, if it were comprised of 9-foot-tall man-eating aliens.
 * I'm a Humanitarian: The Horde. Their word for humans is "cattle" (Other food animals like cows and pigs are "lesser cattle").
 * Lensman Arms Race
 * Lost Technology: The Tunnels of Light and the devices used to power Merki airships.
 * Magnificent Bastard: All the Kazan seem to love this trope, but it applies to Hazin in particular.
 * Manly Tears
 * Multinational Team: The main cast of the 35th Maine - while all American, the officers are two Irishmen, a German, and a Jew. Through the course of the series, they forge an alliance of Russians, Romans, Chinese, Japanese, and Carthaginians.
 * Obstructive Bureaucrat: The Senate always acts like this between wars.
 * Proud Warrior Race Guys: Played with in regards to the various subtribes of the Horde. Played straight with the Tugars (much to their detriment). Somewhat averted with the Merki - Cromwell, a human traitor, helps them get their hands on Union technology, but the Merki do not adjust very well (as it turns out, Proud Warrior Race Guys hate taking non-combat roles). Subverted with the Bantag, who.
 * Purple Prose: Terrible Swift Sword has a lot of elaborate metaphorical narration.
 * Steampunk: The series moves more and more towards this with every book.
 * Superweapon Surprise: The Bantag.
 * We Have Reserves: A common tactic for the hordes, especially Ha'ark.
 * Zeppelins from Another World
 * Zeppelins from Another World