Hyojong of Joseon

King Hyojong initiated a plan to invade Qing China to avenge the humiliation of the 1636 surrender. He expanded the army, built fortifications, and stockpiled weapons. The plan was never executed due to Qing power and lack of allies.

Hyojong strengthened the Joseon military by reorganizing the army, improving artillery, and fortifying northern borders. He also promoted the use of matchlock muskets and trained a standing army, preparing for a potential war with Qing.

King Hyojong died suddenly at age 40, possibly from illness or poisoning. His death ended the Northern Expedition plan. His successor Hyeonjong was young, leading to a power vacuum and intensified factional strife.