The motive of the camp gate as a reverse type became popular during the Licinian and Constantinian periods of civil war. The reverse legend often reads PROVIDENTIAE AVGG. This military type usually depicts a gate set in a block-like structure, a wall or a tower surmounted by turrets (beacons), within the wall doors or door openings. At the top turrets are displayed - on the frontier these were used to signal the next fortification in line. Some camp gates are decorated with arches and dots in the top row.

Rev. Camp gate surmounted by two turrets, star, PROVIDENTIAE CAESS., in ex. SMK.
Obv. Crispus laureate, draped, cuir. bust left, FL. IVL. CRISPVS NOB. CAES.