Yi Sun-sin's career included frontier service, a politically driven imprisonment, loss of rank, and a return through junior service before he obtained a naval command. Once responsible for a regional fleet, he studied the unfamiliar profession, found knowledgeable advisers, reformed organization, and invested in local facilities despite corruption and scarce funding. Yi had already commanded and prepared ships before his famous victories; his strength was systematic preparation rather than sudden inspiration. Debate over when turtle-ship work began reinforces the importance of that advance planning.
Chapter · 39:41-52:27
Yi Sun-sin built readiness before the invasion
Yi's battlefield experience, self-education, local reforms, and investment in infrastructure made his naval district unusually ready when Japan invaded in 1592.