negotiate a truce with the Goths. The attack failed, and when the Gothic cavalry appeared, the Roman cavalry fled, leaving the Roman infantry left wing exposed. The Gothic cavalry then routed the Roman left wing, and the battle was as good as lost. In contrast, the excellent performance of the infantry, both comitatenses and limitanei, is a recurrent feature of Ammianus' history. At the Persian siege of Amida, Ammianus' eye-witness account describes the city's defence by limitanei units as skilful and tenacious, if ultimately unsuccessful. At Strasbourg (357), the infantry showed remarkable skill, discipline and resilience throughout, saving the day at two critical moments.(see Battle of Strasbourg for a detailed account). Even at the disaster of Adrianople, the Roman infantry fought on, despite being abandoned by their cavalry and surrounded on three sides by overwhelmingly superior numbers of Goths. Tactics Just as the armour and weapons of the late army were fundamentally similar to those of earlier eras, so the army's tactics were based on traditional principles. The key elements of systematic scouting, marching formation, battle array, fortified camping, and siegecraft were all followed intact in the late period. This section examines aspects of late tactics that differed significantly from tactics of the Principate. One striking difference was that late army doctrine (and practice) aimed at avoiding open battle with the enemy if possible, unlike the early doctrine from the Principate of seeking to bring the enemy to battle as often and as quickly as possible. The main motivation was likely not a reduced ability to win such encounters. The late army continued to win the great majority of its battles with barbarians. Rather, the primary concern seemed to be the need to minimise casualties. Pitched battles generally resulted in heavy losses of high-grade comitatenses troops, which could not be easily replaced. This in turn supports the hypothesis that the late army had greater difficulty than the Principate in finding sufficient recruits, and especially high-quality recruits. The late army preferred to attack the enemy by stealth or stratagem: ambushes, surprise attacks, harassment and manoeuvres to corner the enemy in zones where they could not access supplies and from which they could not escape (e.g. by blocking mountain passes or river crossings). Where battle could not be avoided, the late army broadly followed traditional practice as regards array. Heavy infantry would be drawn up in a main line, normally straight and