Harry Turtledove. He had 2 books of the Great War series and I asked him about them because they looked interesting. For anyone who doesn't know, Turtledove is one of the premier writers of alternate history. The Great War and American Empire trilogies are based in a universe he created for a one-shot book called How Few Remain. In HFR, Lincoln was pressed to stop the fighting during the Civil War and recognized the Confederacy as a sovereign, independent nation. Flash forward to the early 20th Century (for the Great War series) and the United States of America and the Confederate States of America co-exist on North America, but not peacefully. The CSA has been riding high since seceding from The Union, while the US as never recovered from defeat. Lincoln's Republican Party has all but completely vanished; with the Democrats (lead by President Theodore Roosevelt) occupy the familiar position of pro-capitalism and strong defense. Their counterpart is the Socialist Party: pushing a progressive agenda similar to that of Democrats of the Wilson era. The long animosity between the two nations, and the fact that their loyalties are on different sides of WWI (US with Germany and CSA with England, France, and Canada), creates the unusual circumstance of battles being fought on the continent of North America.
Turtledove does an exceptional job telling the story, but there were always a few things about his style that didn't sit right with me. While engrossing, the books tended to be a slow read. One major complaint (shared by some other fans) is the sheer number of major characters. I've read books in the past with a lot of characters, but Turtledove has at least a dozen major story lines running through his works which hardly ever intersect. Not that its a real problem, but they're not exactly novels that you can put down for a week or two and pick up right where you left off.
With the American Empire series, the problems aren't quite as noticeable (unless I was expecting them and ignored them). There are still multiple threads of the narrative, but they seem to be more manageable. The AE series continues in the same universe mentioned above. In fact, most of the major characters from the WWI series return as major characters in this one (or their families in the case of characters who died). Empire takes place in the period between WWI and WWII and deals with many of the problems that the world faced in those years: treatment of minorities, suffrage, stock market decline, etc. One of the major themes is the rise of a Nazi-type party in the Confederacy, complete with a southern Hitler.
As with his previous trilogy, Turtledove weaves real-life historical figures into his books in fascinating ways. You'll find both Roosevelt presidents, Woodrow Wilson, Upton Sinclair, Joe Kennedy, George Armstrong Custer, and others. His characters are (of course) aging and it would be unreasonable to expect them to carry on into further books, but he manages to transition many of the storylines to future generations in very interesting ways. When a major character dies, their story is usually picked up by a son/daughter, their spouse, or in-laws. One story skipped an entire generation to the character's grandchild. All the events in this trilogy deal with the effects of WWI while building to WWII (Turtledove's Settling Accounts series currently in progress).
If you're interested in reading some good alternate history, I suggest you start with the Great War series (or How Few Remain if you can find it). To quote Larry Bond, "Anyone who loves history will love what Harry Turtledove can do with it."
Great War: American Front, Walk in Hell, Breakthroughs
American Empire: Blood and Iron, The Center Cannot Hold, Victorious Opposition
Posted on the old blog 12/11/2004.