An aquila, or eagle, was a prominent symbol used in ancient Rome, especially as the standard of a Roman legion. A legionary known as an aquilifer, or eagle-bearer, carried this standard. Each legion carried one eagle. The eagle was extremely important to the Roman military, beyond merely being a symbol of a legion. A lost standard was considered an extremely grave occurrence, and the Roman military often went to great lengths to both protect a standard and to recover it if lost. The velites (lightly armed soldiers) wore no armor at all, except a plain helmet. Sometimes decorated with wolf skin or some other unique mark so that the centurions could recognize them from a distance and judge their skill in battle. Image from page 181 of "De militia Romana libri qvinqve : commentarivs ad Polybivm" by Justus Lipsius, 1602 edition.