The history of Ammianus Marcellinus, an officer who had fought in Gaul and on the eastern frontier in the middle of the fourth century, is invaluable, particularly for its detailed accounts of Julian’s expedition against Persia, as well as the Battles of Strasbourg and Adrianople. Much of our knowledge of the organization of the army is based on the Notitia Dignitatum, compiled at some point after 395. This lists the army’s regiments and for border troops their bases, together with the commands to which they are assigned. The Notitia is a challenging document to understand, though good introductions are Brennan, P., “The User’s Guide to the Notitia Dignitatum: The Case of the Dux Armeniae (ND Or. 38),” Antichthon 32 (1998), 34–49, and Kulikowski, M., “The Notitia Dignitatum as a Historical Source,” Historia 49 (2000), 358–377.Google Scholar

Most modern scholarship on the Late Roman army suggests that it was an efficient organization, a change from half a century ago. Few works cover the whole of this period, though for the late fourth century, see Elton, H., Warfare in Roman Europe: AD 350–425 (Oxford, 1996), Nicasie, M., Twilight of Empire (Amsterdam, 1998), and the essays on the Late Empire in Sabin, P., van Wees, H., and Whitby, Michael, eds., Cambridge History of Greek and Roman Warfare (Cambridge, 2007) are also valuable. For discussions of Roman foreign policy (though these are often heavily concerned with individual campaigns rather than theory), Blockley, R. C., East Roman Foreign Policy (Leeds, 1992) and Errington, R. M., Roman Imperial Policy from Julian to Theodosius (Chapel Hill, 2006). On diplomacy, see Nechaeva, E., Embassies – Negotiations – Gifts: Systems of East Roman Diplomacy in Late Antiquity (Stuttgart, 2014). On civil war, there is not much in English, though see Wardman, A. E., “Usurpations and Internal Conflicts in the Fourth Century AD,” Historia 33 (1984), 220–237.Google Scholar

Numbers are discussed in Coello, T., Unit Sizes in the Late Roman Army, BAR S645 (Oxford, 1996). For recruiting, see Speidel, M. P., “Raising New Units for the Late Roman Army: Auxilia Palatina,” Dumbarton Oaks Papers 50 (1996), 163–170, Tomlin, R. S. O., “Seniores-Iuniores in the Late Roman Field Army,” American Journal of Philology 93 (1972), 253–278, and Zuckerman, C., “Two Reforms of the 370s: Recruiting Soldiers and Senators in the Divided Empire,” Revue des Etudes Byzantines 56 (1998), 79–140.Google Scholar

On barbarians, for the Rhine, see Drinkwater, J. F., The Alamanni and Rome (Oxford, 2007); and for the Danube, see Batty, R., Rome and the Nomads (Oxford, 2007). For Persia, see Dodgson, M. and Lieu, S. The Roman Eastern Frontier and the Persian Wars, 226–363 (London, 1991), Greatrex, G. and Lieu, S. N. C., The Roman Eastern Frontier and the Persian Wars, AD 363–630 (London, 2002), Frye, R., A History of Ancient Iran (Munich, 1984), and Dignas, B. and Winter, E., Rome and Persia in Late Antiquity (Cambridge, 2007). On eastern frontier warfare, Coulston, J. C., “Roman, Parthian and Sassanid Tactical Developments,” in Freeman, P. and Kennedy, D., eds., The Defence of the Roman and Byzantine East, BAR S297 (Oxford, 1986), 59–75 and Charles, M. B., “The Rise of the Sassanian Elephant Corps: Elephants and the Later Roman Empire,” Iranica Antiqua 42 (2007), 301–346. For Dura, see James, S., Excavations at Dura-Europos Final Report VII: The Arms and Armour and Other Military Equipment (London, 2004) and James, S., “Stratagems, Combat and ‘Chemical Warfare’ in the Siege Mines of Dura-Europos,” American Journal of Archaeology 115 (2011), 69–101.Google Scholar