Castles were also designed to allow defenders to use firearms to fire on attackers, so there was no longer the need for the depth of moats to be restricted to the length of a spear.
また守城側も火縄銃で攻城側の兵を攻撃できるようになったため、堀の深さをあえて槍の届く程度にとどめる必要がなくなった。