Lord Kalvan of Otherwhen
H. Beam Piper
 Humans on an advanced time-line have discovered "lateral" time dimensions that allow them to travel to "worlds of alternate probability". They use it to exploit natural resources from these alternate realities for their benefit of their home time-line. The Paratime Police are tasked to keep the invention of lateral "time travel" secret (referred to as the "Paratime Secret") and to combat abuses. Occasionally, objects or people get caught in the paratime "conveyors" and are inadvertently transported to alternate timelines. While attempting to apprehend a felon at a remote farmhouse, this happens to Corporal Calvin Morrison of the Pennsylvania State Police. Morrison ends up in a significantly different version of Pennsylvania. Initially confused by the old-growth forest and lack of settlements, Morrison meets some friendly peasants who speak an unknown language. In the middle of a meal, they are attacked by a large raiding party armed with flintlock pistols, which he helps fight off with his police-issue .38 revolver. Reinforcements arrive, but in the confusion, he is shot by the beautiful young woman leading them. Fortunately, the bullet hits his police badge; he is seriously wounded, but not killed. While recuperating, he learns the local language. This alternate version of North America is split up into a number of kingdoms, each composed of small principalities, with a level of technology roughly equivalent to that of the late European Renaissance. Morrison finds himself the guest of Prince Ptosphes of Hostigos — whose blonde, blue-eyed daughter Rylla was the woman who shot him by mistake. He learns that the principality is being threatened by two of their neighbors, Nostor and Sask, with a third, Beshta, hungrily looking on. Ptosphes' overlord, Great King Kaiphranos of Hos-Harphax, refuses to intervene because the priests of the god Styphon want Hostigos to be destroyed. The religious sect uses its monopoly of black gunpowder, known in this timeline as "fireseed", and the secret technique of how to manufacture it, to control the various princes and kings. Hostigos has a sulfur spring; since sulfur is a key ingredient of gunpowder/fireseed, Styphon's House intends to seize that spring once Hostigos is destroyed. Denied gunpowder, Hostigos is certain to be defeated. That is, until Morrison (or Lord Kalvan, as the people begin to call him) organizes production of it in quantity. He also introduces the rapier, improved cannons with trunnions and rifling. With his understanding of military strategy and tactics, he reorganizes the outnumbered Hostigos army and repulses Nostor, capturing an important border town in the process. Then, to undermine the primary enemy (Styphon's priesthood), he sees to it that the secret technique of gunpowder manufacturing is spread far and wide. He assumes that this will soon undermine support for Styphon's House amongst the princes, a tactic subsequently proven correct. Meanwhile, Verkan Vall, a top agent of the Paratime Police, tracks Kalvan down and infiltrates his army. The standard procedure would be to "remove" the displaced person to protect the secret of the existence of alternate timelines by any means judged necessary, generally memory erasure, but other possibilities are committal to an insane asylum or even assassination. Vall takes a liking to the resourceful Kalvan and realizes that his brother policeman has fabricated a background for himself, one that also conceals the Paratime secret. To help persuade his superiors to leave Morrison alone, Vall also recruits historians on the Home timeline. They can now use Kalvan to do an experiment testing the Great man theory — can a single, extraordinary individual change the course of history? After the defeat of Nostor, Sask and Beshta become allies, forcing Kalvan to attack before their armies can unite. After a day of confused fighting against the larger Saskan forces, he emerges victorious once again. Sarrask of Sask is captured and agrees to become a vassal of a new Great King after he learns that he can share in the looting of Styphon's lavish temples. At first, Kalvan proposes that his future father-in-law assume the new throne, but Ptosphes refuses, stating that the other princes would never stand for being ruled by someone they consider only an equal. Kalvan, as an outsider, is the only one they would accept. Plus, his cover story — that he was sent by the gods from a far-away land — plays into local legends. Thus, Lord Kalvan becomes Great King Kalvan of Hos-Hostigos, with Rylla as his queen. When Gormoth of Nostor hears of Kalvan's successes, he turns against Styphon's House himself. This leads to a bloody civil war in Nostor, followed by Gormoth's assassination. His replacement, facing open and implacable opposition from Styphon's House, soon acknowledges Kalvan's sovereignty. Balthar of Beshta at first declines to become subject to Kalvan, until he discovers there are no gunpowder mills in his realm; he then quickly changes his mind. Other neighboring princes soon side with Kalvan, as this gets rid of the usurious taxes and loans levied by Styphon's House (which functions as both a provider of weapons and as a bank). King Kaiphranos is infuriated by the defections, as is the Archpriest of Styphon, but the novel ends at this point. A sequel written by Roland Green and John F. Carr, Great Kings' War, continues the story. Carr further continues the storyline with his novels Kalvan Kingmaker, Siege of Tarr-Hostigos, The Fireseed Wars and the forthcoming The Gunpowder God (which shares the same name as the novelette from which Lord Kalvan of Otherwhen was expanded from).