A long time ago, I'd read
Eric Flint's
Mother of Demons via the Baen Free Library (very sensible anti DRM stance, recommended). I'd enjoyed it quite a bit. In the midst of trying to look up shards for a purely database oriented search, I got distracted by a new series from him.
Starting with
1632, this is a series that follows the events when a 20th century city is transported back into Germany in 1632. In addition to the characters of the time, just the technological changes are very interestingly played out.
Of course, this really appealed to me as on more than one occasion in
Civilization, I've attacked an enemy chariot with Mechanized Infantry....