The identity of workmanship of these arms with the Irish bronze and enamel work suggests that some of those who produced them passed over and found with their traditions and arts a peaceful refuge in the sister isle. Tacitus, however, states most explicitly that the Britons wore neither helmets nor armour, and were not able, therefore, under Caractacus, to maintain their resistance. Herodianus also, relating the expedition of Severus 250 years after Cæsar's invasion, presents an extraordinary picture of savagery. He observes that the Britons were a most warlike and sanguinary race, carrying only a small shield and a spear, and a sword girded to their naked bodies. "Of a breastplate or helmet they knew not the use, esteeming them an impediment through the marshes." They encircled their necks and loins with iron rings as an evidence of wealth, instead of gold, and went naked rather than conceal the tattoos of different animals which covered and gave a blue cast to their bodies. In striking contrast to this picture are the large number of chariots employed in war and the extraordinary skill displayed in handling them. Cæsar states that Cassivelaunus, when totally defeated and a fugitive, was still accompanied by 4000 charioteers; the basis probably of Pomponius Mela's later statement that 4000 two-horsed chariots armed with scythes formed part of that chieftain's army. Having proved ineffectual against Roman discipline, this arm was perhaps soon abandoned, since we find little further mention of war-chariots, though cavalry did not cease to form part of a British army. In process of time the subjugated Britons must have become completely Romanised as to arms, and accustomed to wear the helmet, greaves, and corselet, either of one piece or formed of smaller and more flexible plates or scales. Though the manhood of the country enrolled in disciplined cohorts and legions had deserted it, Roman weapons must have been the arms of those who remained when the Romans finally retired from Britain in 410.