In the Kamakura period this deliberate conduct of hostilities was called kosen (intentional war) and defensive action was called bosen (defensive war), and they were collectively known as 'kosen-bosen'.
鎌倉時代にはこうした意図的な戦闘行為を故戦（こせん）、それに対する防衛を防戦（ぼうせん）と呼び、これらを一括して「故戦防戦」と呼んだ。