Artillery was also used in the Hellenistic era, albeit rarely and without much effect. Catapults and other heavy artillery had a short range, which meant they would have to be up close to the enemy to make an impact. However, this made them vulnerable, indeed 'the difficulty of getting catapults quickly into, and out of, action might make them more of a liability than an asset in fluid warfare'. Machanidas of Sparta learnt this the hard way when his artillery at the battle of Mantinea in 207 BC was quickly taken by Philopoemen's Achaean infantry. Philip V of Macedon used artillery, in conjunction with defensive field works, in his defence of the Aous Valley in the Second Macedonian War, causing high Roman casualties. Antiochus the Great is attested to have used it at Thermopylae, resting it in imposing positions over the prospected battlefield. Perseus of Macedon used artillery in the Third Macedonian War to defend the Elpeus river from Aemilius Paulus, who did indeed move away to seek another route around this defensive line. It was also used in fortified towns to harass enemy assailants. Its use in the battlefield does not seem to have been important, as mass use is not attested until much later, as Arrian clearly suggests in his ""Array against the Alans"".