Originally Posted by some call me tim
I've read the first two books of his "Axis of Time" series and enjoyed them. Also an alternate history story, basically the US Navy of 2020 (or so?) uses an experimental weapon which takes part of the fleet (literally, as some ships are bisected by the spherical nature of the of the effect) back in time to WWII. Ships are scattered all over, some landing in 1942's US Navy, some in Japan, some in other places of the world.
I haven't gotten around to book #3 yet, but the first two were very interesting, seeing the technologies clash, alliances form, and seeing the cultures of two eras butt heads against each other (e.g. how sailors of 1942 would find it unthinkable to receive orders from a black woman as a superior officer).
I'd never read any alternate history books before, but Birmingham has gotten me interested--very intelligently written and plausible. I'll be sure to check Without Warning out at some pont.
I'm on the 3rd book of the Axis of Time series. I really like how Birmingham presents many little things that are different between our 'now' and their 'now'. For instance, how up-timers seem more cold about killing even the innocent if they threatened the mission than the 'Temps' and how even the most battle hardened and self centered 'Temps' find this attitude most unsettling. Or how women of the two eras generally walk and carry themselves. Or how California smog that caused the 'Temps' problems still seemed like fresh air to the uptimers!
None of this stuff really moves the story along, but it raises the feel of realism for the reader (at lest for THIS reader!)
As for this being your first Alt. History book, you are starting at a pretty high quality. You might find yourself a bit disappointed in some other authors. But take a look at Harry Turtledove and Robert Conroy.