The legions of the late Republic and early Empire are often called "Marian" legions. Following the Battle of Vercellae in 101 BC, Marius granted all Italian soldiers Roman citizenship. He justified this action to the Senate by saying that in the din of battle he could not distinguish Roman from ally. This effectively eliminated the notion of allied legions; henceforth all Italian legions would be regarded as Roman legions, and full Roman citizenship was open to all the regions of Italy. At the same time, the three different types of heavy infantry were replaced by a single, standard type based on the "Principes": armed with two heavy javelins called "pila" (singular "pilum"), the short sword called "gladius", chain mail ("lorica hamata"), helmet and rectangular shield ("scutum").