A sally port is a secure, controlled entryway to an enclosure, such as a fortification or prison. It typically has protective features like two sets of doors that can be independently barred to delay unauthorized access. Historically, it allowed troops to make sorties during a siege while maintaining the defensive strength of fortifications. In modern terms, especially in law enforcement and corrections, a sally port is a secure garage-like area where prisoners are safely transferred between vehicles and buildings, with controlled access to prevent escapes or unauthorized entry.
