Ross Cowan was formerly a research student at the University of Glasgow where he was recently awarded a PhD for a thesis on the Roman army entitled 'Aspects of the Severan Field Army AD 193-238'. The major themes of the thesis are the organization of the Praetorian Guard and Legio II Parthica, their recruitment, numbers and equipment. Ross also completed his first degree at Glasgow. In 1999 he was elected a fellow of the Society of the Antiquaries of Scotland. The author lives in Glasgow, Scotland.

?INTRODUCTION: The size and organization of the legion – campaign attrition – From maniple to cohort: the cohort's functional identity – command structure – Basic battle formations – Intervals in the battle line: control and cohesion – the – interval as a channel for attack and a defensive trap –
the size of intervals · LEGIONARY BATTLE LINES AND MANOEUVRES: Simplex acies: Forum Gallorum, 43 BC – Ruspina, 46 BC – Carrhae, 53 BC: disastrous result of the abandonment of the simplex acies – Duplex acies: Ilerda, 49 BC – Maximinus' agmen quadratum, AD 238 – Arrian's array against the Alans, AD 135 – Triplex and quadruplex acies: Ilerda, 49 BC – the {muthul}, 109 BC – Chaeronea, 86 BC – Pistoria, 62 BC – Caesar in Gaul, 58 BC – Pharsalus, 48 BC: the devotio – Uzzita, 46 BC – the Rhyndacus, 85 BC: use of field entrenchments – Thapsus, 46 BC: mixed triplex and quadruplex acies – Second Philippi, 42 BC – Detached forces and surprise attacks: Tigranocerta, 69 BC – Aquae Sextiae, 102 BC: the morale value of noise – Lauron, 76 BC – Segovia, 75 BC: the refused centre – Downhill and uphill charges: Mts Armanus & Gindarus, 39 & 38 BC – Ilerda and Dyrrachium, 49 and 48 BC – First Philippi, 42 BC – Mons Graupius, 84 AD
·OFFENSIVE AND DEFENSIVE FORMATIONS: The cuneus and 'pig's head': use at Bonn, AD 69 – in Britain, AD 61 – at Cremona, AD 69 – The orbis: use at Cirta, 105 BC – by Sabinus and Cotta, 54 BC – by Caesar in Britain, 55 BC – by Chariovalda in Germany, AD 16 – by legio XXXVI at Nicopolis, 47 BC – at Adretum, AD 9 – on the Danube, AD 173/174
– The testudo: use at Issus, AD 194 – at Daphne, AD 272 –
at Cremona, AD 69 – The agmen quadratum and testudo: in Mark Antony's retreat from Media, 36 BC – failure against Ardashir, AD 233 ·EPILOGUE: Adrianople, AD 313 – Ctesiphon, AD 363 ·REFERENCES AND FURTHER READING·PLATE COMMENTARIES·INDEX