One Second After by WILLIAM R. FORSTCHEN
Forstchen also wrote a series of at least ten books collectively called The Lost Regiment. They are about a Civil War Union Regiment that is mysteriously transported to an alien planet where they encounter people from Earth who were abducted in other eras and have to engage in a protracted war with a nation of alien barbarians who are pillaging the planet.
Jerry Pournelle wrote a series of thee books, called Janisaries, about a group of CIA contractors who are abducted by aliens and dumped on another planet to raise plants used to make recreational drugs. There was supposed to be a fourth book but it has never been completed.
In today's column on the Backwoods Home web site, Massad Ayoob talks about a future movie called Alexander's Bridge. It is about a Delta Force team that gets transported back through time to the middle of the Civil War. The cast will consist of real life Delta Force operators and Civil War re-enactors. Ayoob says they intend to get the details right about weapons, tactics, clothing, etc.