The cohort 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 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. Thus the three different types of heavy infantry (the "Hastati", the "Principes" and the "Triarii", which composed the pre-Marian Roman armies) were replaced by a single, standard type of legionary based on the "Principes".