"Velites" did not form their own units; a number of them were attached to each "maniple" of "hastati", "principes" and "triarii". They were typically used as a screening force, driving off enemy skirmishers and disrupting enemy formations with javelin throws before retiring behind the lines to allow the heavier-armed "hastati" to attack. They were normally the ones who engaged war elephants and chariots if they were present on the field, such as in the Battle of Zama, in 202 BC. Their high mobility and ranged weaponry made them much more effective against these enemies than heavy infantry. An early Roman legion contained approximately 1,000 "velites". "Velites" were eventually disbanded after the Marian reforms. Lucilius suggests that "rorarii" and "velites" were interchangeable, with "velites" gradually superseding "rorarii". Another theory is that the "leves"' equipment was upgraded until they were at the same level as the "rorarii", and they both collectively became known as the "velites".