going into battle; departure for the front
appearing (in a match)
starting an election campaign
武将が出陣の合図を鳴らした。
The general sounded the signal to march out.
出陣前に兵士たちが士気を高めた。
Before departing for battle, the soldiers boosted their morale.
城を出て出陣した武士たちは戻らなかった。
The samurai who left the castle for battle never returned.