Return Engagement is the first of the Settling Accounts trilogy, which is the latest in the Great War series. The series started back in 1998 with the publication of How Few Remain, which is by far the best of the whole series. Then followed the Great War series (American Front, Walk in Hell, and Breakthroughs) from 1998-2000, detailing a very different First World War. THEN we had the American Empire trilogy (Blood and Iron,The Center Cannot Hold, and The Victorious Opposition) in 2001-2003.
Now it's time for the Settling Accounts trilogy. Return Engagement starts with the death of a character I had long hoped would just die, so I was happy. Another character I had wondered about survived. I'm still not sure whether to be happy for this one or not.
The book starts with the attack everyone (except the US government, apparently) saw coming. Jake Featherston, the Hitler-character in this reality, invades Ohio from newly-Confederate Kentucky—blitzkreig-style. Things progress fairly predictably after that—the Confederacy gains territory, the US is in a panic, characters who were in the army in the last series consider re-enlisting to fight the Confederacy. Each aspect of World War II in our time-line is duplicated somehow in this alternate history—which is annoying.
I stopped reading Turtledove's Darkness series because it was obviously World War 2 with magic. Now he's shifted World War II to North America, replacing Nazi Germany with the CSA, and the Jewish Holocaust with... well, some might consider that telling, though anyone who has read the previous offerings (or even thinks about the history of the Confederacy in our own history) could figure it out.
The characterizations are the same. We read about the same sailor who is perpetually sunburnt (and we're always reminded of this whenever the poor guy has to go somewhere hot—I started wishing he'd spend time in the North Atlantic, just to get a change of exposition!), the same saboteur in Canada, the same American lawyer-turned-fighter pilot. Morrel (guess who HE represents in our time line!) is still an under-appreciated tank commander whose ideas are ignored by those in charge. Dowling is still living in Custer's shadow, years after the latter's death. Nothing has changed.