expression
continued luck in the fortunes of war
A formal, somewhat archaic yojijukugo used to wish a warrior lasting success in battle. Often seen in historical contexts or as a set phrase.
武将は家来たちに「武運長久を祈る」と言った。
The warlord said to his retainers, 'I pray for your continued luck in battle.'
A yojijukugo composed of 武 (military), 運 (luck), 長 (long), and 久 (lasting). The exact historical origin is uncertain, but it has been used as a set phrase to wish warriors enduring fortune in battle.