Yesterday was the anniversary of the Battle of Antietam, which was the beginning of the end for the South. (A Dog’s Life and others commemorated it.) But no one noted that this battle is also memorable for having turned on a single accident, and could easily have turned out differently. A Confederate courier, entrusted with Special Order 191 (Lee’s detailed, division-by-divison plans for the battle), wrapped it around some cigars and rode off hell-for-leather—and dropped the orders, which were found by a Union picket and passed up to McClellan. The resulting victory, and Lincoln’s Emancipation Proclamation, convinced England not to recognize the Confederacy and doomed the South to defeat.
For a vivid look at what might have been, pick up Harry Turtledove’s Great War series, starting with How Few Remain, which begins in 1881 in a world in which the courier did not lose the orders, and the Union lost the battle and eventually the war. In this first book, the Union is defeated again in what would have been the Mexican-American War in our world.
In The Great War: American Front, The Great War: A Walk in Hell, and The Great War: Breakthroughs, WWI is fought between an alliance of the Union (headed by Teddy Roosevelt) and Imperial Germany (headed by Kaiser Bill), and the Confederacy, England, and France. The Union and Germany are triumphant.
In American Empire: Blood and Iron, American Empire: The Center Cannot Hold, and a book whose title hasn’t been announced yet, the victors impose Versailles-like terms on the South and…well, guess whose analogue pops up in the South!
The series has a strong narrative drive, and its structure, which follows a small number of recurring characters (some of whom die), keeps one engaged. Especially entertaining are the treatments of characters from our own history—Custer, Lincoln, Samuel Clemens, et al—and what they might have been under different circumstances. If you’re looking for philosophical depth in your alternate history, like that found in Philip K. Dick’s Man in the High Castle, you won’t find it here, but that is not, I think, what Turtledove is after. He’s more interesting in holding up a mirror to the reader and letting them find themselves in these stories of Americans and their struggles against those who threaten their way of life—and he does that very well.