Very few alternate history tales herein. The few in which history turns into another track tend to address the turning point rather than the result ("The Lion Hunt").
Dann, Jack: "Good Deeds" Portrayal of Robert Kennedy slumming in New York City, indulging in low company, ethnic slurs, police brutality in the company of people he trusts because he can buy them. Strains the definition of "conqueror" and isn't alternate history but interpretation.
Dedman, Stephen: "Twilight of Idols" A woman whose father was determined to find historical truth behind the Norse legends as Schliemann did for Homer's tales hired a half-failed set designer - Adolf Hitler - to help find Fafnir's lair. One who bathes in Fafnir's blood is said to become invincible...
Di Filippo, Paul: "Observable Things" (Robert Howard's Solomon Kane) Told in 1st person, old fashioned diarist style (a lot of odd capitalization for emphasis), by a Puritan reminiscing about his youth, when he trailed after Kane.
Effinger, George Alec: "Walking Gods" Saladin narrates his own story, beginning with his youth as an officer under his uncle, their campaigns together, and how he came to be vizier of Egypt. But the main thrust of the story is how Saladin and his army came to the rescue of another alternate history - the rescue of Xenophon, more than 1500 years before. Story worth reading.
Johnson, Kij: "The Empress Jingu Fishes" She is a seer, cursed in that to her there is little to choose between matters past, present, and future. Her only cold comfort is to force the gods to give her omens - such as allowing her to catch trout with a needle - before she does what they command.
Malzberg, Barry N.; Pronzini, Bill: "Intensified Transmogrification" The opening will get one's attention: "Let me remind you of the way it was before he tried to seize absolute power, declare a state of national emergency, enact martial law, create nuclear holocaust." Narrated by an unnamed aide close to Lyndon Johnson, but from memory in an unusual style: the dialogue isn't given in quotations, and emphasizes the narrator's opinions of Johnson's mental state. "I was Lyndon's closest advisor then. Such being an inaccurate description, since Mr. President took no advice from anyone..."
Morrow, James: "Martyrs of the Upshot Knothole" - codename for a certain series of 1950s atmospheric nuclear tests. The narrator replaces Agnes Moorehead, who played John Wayne's mother in THE CONQUEROR, arguably his worst film, and predeceased him by several years. Her current flame has spotted a connection between several cases of cancer and the location shooting in 1956. [OK, but the truth needed no embellishment by imaginary characters or extreme F/SF elements.]
Roessner, Michaela: "Del Norte" Claims to be based on a true story. (The author herself discourses a little on the topic of 'truth' at the end.) Joan Grau, one of Cortez' companions, brought back a bride from the strange lands across the sea - and the children of the village were overjoyed. If a princess could really live here, *anything* could happen...(Mostly from her viewpoint, though, as a stranger in a strange land remembering fallen Tenochtitlan.)
Sargent, Pamela: The protagonist Jamukha is the "Spirit Brother" of the man he once knew as Temujin: Genghis Khan. Having broken his dying oath to watch over Temujin - intended half as revenge for his own death - he falls into the power of Temujin's chief shaman, who seeks a tool in his own quest for political power. Jamukha here is portrayed as both spurned ex-lover and boyhood friend.
Watson, Ian: "An Appeal to Adolf", unlike most of the other stories herein, contains explicit sex and strong language thanks to the narrator's preoccupation with concealing his sexual relationship with a fellow soldier in the force invading Britain by sea in this alternate history. Very disturbing viewpoint character coupled with way-out "science" (powered aircraft don't exist).
Webb, Janeen: Philip of Macedon and his son Alexander ride out on "The Lion Hunt", wherein an assassin with a poisoned lance proves how fragile history can be.
West, Michelle: "To the Gods Their Due" Alexander, narrating his own story of growing alienation from his other half, his best friend Hephaestion, who chooses not to follow Alexander too deeply on his journey from first-among-equals ruler of Macedon to a god-king of Egypt.
Zebrowski, George: "Nappy" (Napoleon) opens in the voice of an historical scholar, discoursing on the Virtual Dark Age - in which it is artfully made clear that humanity become so fascinated with virtual reality scenarios that attempts at achievements in the *real* world were let slide. (The tone is *so* realistically academic, in fact, that it risks losing readers who don't care to slog through scholarly tomes.) Then the story discusses the innocent beginnings of that age: one historian's fascination with the character of a virtual reality reconstruction of Napoleon, an AI aware of his hopeless situation, endlessly experiencing scenarios without true victory - the world never becoming what he'd hoped for when he set out to conquer. (Also contains a bit of philosophical speculation on the nature of conquerors.)