The clipeus was used by Romans during the Roman Kingdom and early republic but was replaced by the legionary scutum, a convex rectangular shield, in the later Roman Republic. However, the scutum disappeared during the Crisis of the Third Century. All troops adopted the auxiliary oval (and sometimes round or hexagonal) shield (parma or clipeus).
The curved shield was utilized by Romans from the Roman Kingdom and early republic periods but was eventually superseded by the more substantial legionary scutum, a convex rectangular shield, in the later Roman Republic. However, the scutum ceased to exist during the Crisis of the Third Century. Consequently, all troops transitioned to using the auxiliary oval (and sometimes round or hexagonal) shield (parma or clipeus).