To fight on the Korean Peninsula in ancient times without communications, the headquarters would require to be placed in northern Kyushu close to the battlefront, otherwise, timely and proper measures or orders for battle couldn't be carried out.
通信手段が未発達な古代にあって朝鮮半島で戦うには、司令部は前線近くの北部九州に置かなければ戦闘に間に合う適切な判断や指示は下せない。