In the "Axis of Time" trilogy, a 21st-century United Nations naval task force is flung back in time to the Battle of Midway during WWII. They join the Allies, and change history. An interesting bit is how the 21st-century forces have to spend much of their time dealing with murderous racist sexist homophobic asshats that are nominally on their side. I have the first book in trade paperback, the last two in hardcover.
In the "Without Warning" trilogy, a weird energy field suddenly kills nearly everyone in North America. The world balance of power shifts dramatically. Some countries move to salvage the equipment and resources, while surviving US miltary forces in Iraq, Cuba, and the Pacific oppose them.
If you'd like these, please comment. If multiple people want them, I'll give preference to the ones with lowest postage costs, and then flip a coin. If postage costs would exceed the cost of picking them up at your local used bookstore, I'll find a home for them locally. NOTE: US Customs requires me to get the full legal name, home address, and telephone number of recipients in the US.