With King Sejong the Great having ascended to the throne in Joseon Korea only the previous year (1418), former King Taejong still held de facto power, and it was Taejong who decided to launch an expedition against Tsushima in June 1419 under the pretext of pacifying the Wako, dispatching a fleet of 227 ships and 17,285 soldiers to invade Tsushima, with general YI Jong Mu in command.
李氏朝鮮では前年に世宗(朝鮮王)が即位していたが、実権は太宗(朝鮮王)が握っており、太宗は倭寇撃退を名目にした対馬遠征を決め、永楽17年（西暦1419年）6月、李従茂率いる227隻、17,285名の軍勢を対馬に侵攻させた。