[Sa'ar Chasm]

I read a lot of Harry Turtledove. He's been described as the Master of Alternate History. His series include the Worldwar tetralogy (the titles all include the word Balance), various Videssos series, something called Southern Victory that's up to ten novels so far, plus a few other stand-alones or nascent trilogies (like what would have happened if the Japanese had sent a landing force along with the air raid on Dec. 7, 1941).

Caveat: while the actual alternate history is interesting, Turtledove cannot write dialogue or prose. Most of his characters spend all their time stating the obvious and then telling each other they're correct (when they're not being shot at, bombed or shelled, that is). I tend to skip vast chunks of text since there's nothing happening except wooden character lack of development.