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troop headquarters; stronghold
inn designated for use by a daimyo (Edo period)
本陣は静まり返っていた。
The headquarters was dead silent.
選挙運動の本陣に支持者が集まっている。
Supporters are gathering at the campaign headquarters.
敵の本陣を一気に攻め落とす作戦が動き出した。
The plan to capture the enemy stronghold in one stroke began to move.