Yi himself had never been trained as a naval commander. Korea, called Joseon at the time, did not have any naval training facilities. Although Yi passed the military exams when he was young, he was never trained at an academy. Yi's only military experiences came from fighting Jurchen tribes. In fact, the Battle of Okpo, his first victory against the Japanese fleet, was also his first sea battle ever. None of his subordinates, including his own staff, had ever fought at sea before.