The early Roman army was based on a compulsory levy from adult male citizens which was held at the start of each campaigning season, in those years that war was declared. There were no standing or professional forces. During the Regal Era (to c. 500 BC), the standard levy was probably of 9,000 men, consisting of 6,000 heavily armed infantry (probably Greek-style hoplites), plus 2,400 light-armed infantry ("rorarii", later called "velites") and 600 light cavalry ("equites celeres"). When the kings were replaced by two annually elected "praetores" in c. 500 BC, the standard levy remained of the same size, but was now divided equally between the Praetors, each commanding one legion of 4,500 men.