The Rogue Son-in-Law in a Chaotic Age

[Alternate history, son-in-law, farming, rise to power] Qin Xian, a chemistry master's graduate, unexpectedly transmigrates into an unfamiliar age of chaos and becomes a low-ranking officer in a defeated army. From the start, he marries a landowner's daughter, protects the villagers, fights bandits, and repels foreign invaders. A prince commanding a powerful army, the Empress of Great Wei, and the princess of Great Xia all see me in a new light...