How Few Remain is Harry Turtledove's excellent beginning to his Southern Victory (AKA "Timeline-191") series. It takes place in a universe where General Robert E. Lee's Special Order 191 was never discovered by Union troops, thus dramatically changing the course of history.For those of you who aren't US Civil War'buffs', as they are apparently known in the USA, Order 191 contained extensive information about the rebel General Lee's proposed troop movements during his famous offensive campaign to take the US's capital. Because George McClellan had this information, he was able to position his troops in areas to ambush them. The Battle of Antietam was the bloodiest battle of the Civil War, and—both morally and mortally—diminished the Confederates. It was perhaps the most vital turning point in the entire war.And in this universe, it never happened.Lee marched into Washington and the Confederacy was recognized as a nation-state by Britain and France, who mediated a peace settlement. Abraham Lincoln was never assassinated. Both Stonewall Jackson and Jeb Stuart survive the war. Samuel Clemens stays in San Francisco, instead of writing fiction.In short: Hilarity Ensues.The story picks up in 1881, when the Confederates' purchase of the Mexican territories of Chiuhuahua and Sonora prompts U.S. President James G. Blaine to declare war on the Confederacy.The story follows, in turn, eight historical figures:
Thomas J. Jackson, old "Stonewall", General-in-Chief of the Confederate Army, is ready and eager to strike at the Yankees once more.
General J.E.B. Stuart defends the new Confederate territories from the Yankees, the Apaches under Geronimo being first his allies and then his foes.
Colonel George A. Custer, a frustrated Yankee cavalryman, serves on the Great Plains and helps put down the Mormon rebellion in Utah.
... which wasn't a real strategy, just a thought experiment (just look at that Other Wiki article - not a single primary source, albeit on account of the fact that none exists). But the breadth and depth of the stuff Turtledove touches makes it inevitable he'll fall behind the cutting-edge of historical research somewhere, especially as new research surfaces. Though there was that egregious depiction a WWII Chinese peasant as both liking the Chinese Communist Party and believing that it fights Japan (and that the Guomindang doesn't!) that sounds like it was lifted verbatim from a PRC school-textbook.
Antebellum America: Unlike some attempts to show what the world would be like if the Confederates won, How Few Remain actually explores socio-economic and cultural issues that don't have to do with slavery.
Bad Ass: Custer and Roosevelt live their lives doing this. The rest of the main cast have their own, in their own ways.
Lincoln and Douglass are both retired badasses, who are really getting too old for this, but that doesn't stop either of them for a minute.
Early-Bird Cameo: Hosea Blackford, for later in the series. He's just a kid from a mining town who runs into Lincoln on the train. There's also a very brief appearance by the girl who will later carry the name of Nellie Semproch; she's a child who runs out into the street in Washington, D.C.
For Want of a Nail: The novel—and the ten-novel series that follows it—is all happening because one tiny detail, the finding of Order 191. Which could so very easily have happened in this universe. And if it did, it would have (if not necessarily guaranteed a Confederate victory) given Lee an incredible strategic advantage which might well have changed the course of the war.
It's even lampshaded in the prologue, where the messenger who dropped the Order is effusively telling the two soldiers who noticed it how grateful he is, and how "this could have cost us the war!"
Not as much so in the rest of the Timeline-191 series, where the famous people rub elbows with an extensive cast of Turtledove originals.
Invaded States of America: San Francisco is shelled and raided by the British. A British invasion of Montana is defeated in what turns out to be the highlight of the war for the USA. Northern Maine is ceded to Canada as part of the peace settlement.
Start My Own: When his local recruiting-station won't take volunteers, Roosevelt takes it on himself to pull together his own Unauthorized Regiment.
Start of Darkness: After being humiliated by the Confederacy again, von Schlieffen offers the USA an alliance with the German Empire, later leading to the USA becoming a brutally ultra-militaristic, German-trained power.