The Byzantine Army

The Byzantine army had a reputation among its neighbours for being difficult to fight and reluctant to fight — an army that shadowed you for weeks, cut off your foragers, ambushed your column in a pass, and declined battle unless the odds were clearly favourable. That reputation was earned deliberately. Byzantine military writing is unusually candid about the reason: the empire could not replace a destroyed field army quickly, and an emperor who lost one could lose a province in the following campaigning season. Caution was doctrine, not cowardice.

That doctrine survives in a body of technical literature unmatched anywhere in medieval Europe. The Strategikon attributed to the emperor Maurice (c. 600), the Taktika of Leo VI (c. 900), the anonymous tenth-century treatise On Skirmishing, and the Praecepta Militaria of Nikephoros II Phokas together describe recruitment, drill, marching order, camp layout, signalling, siegecraft and the specific habits of each enemy. They are the reason we know more about how a Byzantine army functioned than about almost any other pre-modern force.

Three Armies, Not One

The institution changed shape completely at least twice, and it is misleading to speak of a single Byzantine army.

The Late Roman Army, to c. 640

Down to the Arab conquests the empire fielded the army Diocletian and Constantine had built: mobile field forces (comitatenses) under the command of magistri militum, frontier troops (limitanei) garrisoning fortified lines, and an elite guard. Units were numbered and named in the old Roman way; the language of command was Latin long after the language of government had shifted to Greek, and Latin drill words survive fossilised in Greek manuals centuries later.

The striking arm by the sixth century was heavy cavalry. Procopius, describing Belisarius’s troops, is explicit that the Roman horse archer — armoured, able to shoot from the saddle and also to close with a lance — was what gave Justinian’s armies their advantage in Italy and Africa.

The Thematic Army, c. 660–1050

The catastrophe of the seventh century made the old structure unaffordable. What replaced it was the theme system: the surviving field armies were settled across Anatolia, and soldiers held land on the obligation of military service, mustering under the general (strategos) who also governed the province.

The advantages were fiscal and strategic. A thematic army cost little in cash, it was rooted in the ground it defended, and it could be mobilised for a season and sent home. The disadvantages appeared later: it was a defensive instrument, slow to concentrate, and its loyalty belonged as much to its strategos as to the emperor — thematic revolts are a recurring feature of the eighth and ninth centuries.

Alongside the themes the emperors kept professional regiments at the centre, the tagmata, based in and around Constantinople. These were full-time, paid, better equipped, and used as the striking force on campaign.

The Professional and Mercenary Army, c. 1050–1453

By the eleventh century the thematic obligation had largely been converted into cash payment, the smallholdings had been absorbed by great estates, and the empire was buying soldiers instead: Normans, Franks, Turks, Russians, Georgians, Pechenegs, Alans, Catalans. The Varangian Guard is the famous case.

Mercenaries were effective and expensive, and their loyalty was contractual. The defeat at Manzikert in 1071 is often blamed on mercenary treachery; the deeper problem was that a state which had stopped producing its own soldiers had also stopped being able to absorb a defeat.

Organisation and Ranks

The tenth-century army was organised in a nested structure that the manuals describe carefully:

Unit	Approximate strength	Commander
Bandon	200–400	komes
Droungos / moira	1,000–3,000	droungarios
Tourma	3,000–5,000	tourmarches
Theme or tagma	4,000–10,000	strategos / domestikos

Numbers in the sources should be treated with suspicion — establishment strength and actual strength were rarely the same — but the ratios are consistent. A large field army of the tenth century might be twenty to thirty thousand men; the armies that fought the Bulgars or the Arabs were usually much smaller.

Equipment

The tenth-century heavy cavalryman (kataphraktos) described in the Praecepta Militaria wore a mail or lamellar corselet, a padded garment over it, splinted or lamellar limb defences, and a mail hood and helmet leaving only the eyes exposed. His horse was armoured on the head, neck and chest. He carried a heavy lance, a sword, and often a mace — the Praecepta specifies iron maces for the front ranks of the wedge, since armour had outrun the cutting sword.

Infantry were divided into skoutatoi, heavy spearmen with large oval or round shields, and archers and javelineers stationed behind them. The standard formation was a deep infantry square or oblong with gaps through which cavalry could sortie and retreat — an arrangement designed specifically so that a defeated cavalry charge would not become a rout.

The composite bow was the standard missile weapon; Byzantine archers shot with the thumb-ring draw learned from the steppe. Crossbows appear from the eleventh century, introduced from the west, and Anna Komnene describes the weapon with fascinated distaste as “truly a diabolical machine.”

How the Byzantines Fought

Three principles run through the manuals.

Avoid the decisive battle. On Skirmishing, written for commanders facing Arab raiding columns in the Taurus, is essentially a handbook of shadowing, ambush, night attack on camps, and cutting off the return route with the plunder. The raid was to be made unprofitable, not defeated.

Know the enemy in detail. Both Maurice and Leo VI include ethnographic chapters describing how Persians, Franks, Lombards, Slavs, Avars and Turks fight, camp, and can be provoked or avoided. The advice is specific: Franks charge hard and cannot sustain, so give ground and strike the flank; Turks feign flight, so never pursue far; Slavs fight in forests and marshes, so do not follow them there.

Combine arms and keep a reserve. The characteristic Byzantine order of battle had an infantry centre, cavalry wings, a flanking detachment placed to take the enemy in the side, and an explicit rear reserve. The manuals return repeatedly to the danger of a general committing everything at once.

Discipline, Religion and Pay

Soldiers were paid in cash, in donatives at an emperor’s accession, and in a share of plunder regulated by custom. The tagmata were paid annually in a ceremony at the palace that the Book of Ceremonies describes in detail.

Campaigns opened and closed with liturgy. Armies carried relics and icons; the Trisagion was chanted before an engagement; a battle standard might incorporate a fragment of the True Cross. This was not decoration. The soldier’s sense that he fought under divine protection was actively cultivated, and Byzantine writers noted the contrast with Islamic ideas of martyrdom in war. Nikephoros II Phokas is said to have asked the church to recognise soldiers killed fighting the Arabs as martyrs and to have been refused — the church’s position being that killing, even in a just war, required penance. The story comes from a later source and may be a construct, but the doctrinal position it describes is genuine and was held consistently.

The Army and Politics

Between 610 and 1081 the imperial throne changed hands by military coup more often than by peaceful succession. Successful generals — Heraclius, Leo III, Nikephoros II Phokas, John I Tzimiskes, Alexios I Komnenos — took the throne, and unsuccessful ones were blinded or tonsured. The consequence was that emperors spent a great deal of effort keeping commands divided, rotating generals, and preferring eunuch commanders who could not found dynasties. Narses, the conqueror of Ostrogothic Italy, is the most distinguished example; the practice is discussed in Byzantine eunuchs.

Decline

The eleventh-century collapse had structural causes. The thematic soldiery had been squeezed out by the growth of great estates; the civil aristocracy of the capital deliberately ran down the army budget after the frontier was quiet in the 1020s; and the cash economy made it easier to hire foreigners than to maintain provincial obligations. When the Seljuks arrived, the empire could field armies but not replace them.

Alexios I rebuilt a force around the imperial household, aristocratic retinues and foreign contingents, and it worked well enough for a century. The Fourth Crusade ended it. After 1261 the Palaiologan emperors never had more than a few thousand soldiers of their own, and the defence of Constantinople in 1453 was conducted largely by foreigners.

Logistics

The manuals are unusually interested in supply, because the Byzantines had learned what happens without it.

A campaigning army carried grain, biscuit (paximadion, twice-baked and effectively imperishable), salt meat, wine and vinegar, and drove livestock with it. The Praecepta and the tenth-century treatises on imperial expeditions specify the mule and cart train, the number of days’ rations, the collection points along the route and the officials responsible.

Provisioning was organised as a state obligation. Themes along a march route were required to have supplies stockpiled at designated depots (aplekta) — Malagina, Dorylaion, Kaborkin and others in Anatolia — and the army moved between them. This is why Byzantine campaign routes are so predictable in the sources: they follow the depots.

Foraging was regulated and, on Byzantine territory, punished if it turned to plunder. Nikephoros II’s legislation on the subject is severe, and the reasoning is fiscal rather than humane: a devastated theme pays no tax and supplies no recruits.

The Treatises

The technical literature is the field’s greatest asset and deserves naming, because a reader can go to it directly in translation:

Work	Date	Content
Strategikon of Maurice	c. 600	Drill, formations, ethnography of enemies
Taktika of Leo VI	c. 900	Comprehensive; updates Maurice
On Skirmishing	c. 950s	Frontier warfare against Arab raids
Praecepta Militaria	c. 965	Nikephoros II on the tenth-century army
Taktika of Nikephoros Ouranos	c. 1000	Expanded version of the above
Treatises on imperial expeditions	10th c.	Logistics and ceremonial of campaign

On Skirmishing is the outstanding one. It was written by a commander who had spent his career on the Taurus frontier, and it is entirely practical: how to place lookouts on which peaks, how to shadow a raiding column without being drawn into battle, how to hold the passes on the return route, how to attack a camp at night. There is nothing comparable in western Europe before the early modern period.

What the Army Was Not

Two corrections are worth making against the popular picture.

It was not a Roman legionary army. The legion had ceased to exist as an organisational form by the fourth century, and nothing in the Byzantine structure descends from it directly. The continuity with Rome is institutional and administrative, not tactical.

And it was not unusually large. Byzantine field armies of the tenth century, at the empire’s military height, ran to twenty or thirty thousand men, and most operations involved a few thousand. The impression of vast imperial hosts comes from chroniclers’ numbers, which are rhetorical.

• The Theme System — the provincial army that held Anatolia
• The Varangian Guard — the emperor’s axe-bearing foreigners
• The Byzantine Navy — the other half of imperial defence
• The Battle of Manzikert — the defeat that exposed the system
• The Byzantine–Bulgarian Wars — three centuries of Balkan campaigning
• The Walls of Constantinople — the fortification the army never had to replace
• Byzantine Diplomacy — the cheaper instrument, always preferred