The Byzantine Empire has a long military history, and the structure of it’s military forces varied as the nature of warfare changed. One of the earliest changes was the addition of regular cavalry to roman infantry legions. Later the Theme system, consisting of military forces protecting land grants was adopted. Finally, the Byzantines did NOT use uniform unit sizes as this allowed them to keep their enemies from guessing their true strength. Because of the wide variety of organization in the Byzantine military, I’ve decided to go with a semi-historical approach to simplify the end results.
Note: Byzantine military titles are derived from both Latin and Greek sources.
Cataphract - From the Greek, Kataphraktos (meaning "armored"), a heavy cavalryman. Cataphracts were armored with conical helms and chain or scale armor known as lorikon, additionally, a thyreos (small, round shield) was used. Armament was typically a composite bow, kontarion (lance), with a spatha or paramerion (scimitar) as the primary backup weapon, and a mace or battle axe as a secondary backup weapon
Skoutatoi - These heavy infantry formed the majority (roughly 70%) of the Byzantine infantry. Their name derives from the skouton, a large oval-shaped shield. In addition they were armored with simple conical helms, kremasmata (an armored skirt), livanion (a sleeveless lamellar cuirass typically augmented with pteruges (leather strips worn to protect the shoulders)), and epilorikion (a padded leather garment worn over the cuirass). Their arms included a spatha (double-edged sword) and kontarion (two to three meter long pike). In battle formations, they filled the first seven of ten ranks.
Toxotai - Byzantine light infantry were typically archers, employing a composite bow with a spatha or tzikourion (small axe) for close combat. They were generally wore only a kavadion for armor. They were employed as the final three of ten ranks in battle formations.
Menavlatoi - A specialist variant of the Skoutatoi, more lightly armored, employing a smaller shield, but armed with a much stouter type of pike (Menavlion) .
Peltastoi - Unarmored light infantrymen, armed with javelins
Tetrarch - Leader of a "Rear Guard," composed of four men.
Pentrarch - Leader of a "Vanguard," composed of five men.
Decarch - Leader of a Decharchy, composed of one Rear Guard and one Vanguard, for a total of ten men.
Pentecontarch - Leader of five Decharchia, unit total of 50 men.
Hecatontarch - Leader of a cavalry century.
Kentarch(os) - Leader of an infantry century.
Komes - "Count," Leader of a Banda/Bandum.
Chiliarch - Leader of an infantry chiliarchy.
Domestikos - Leader of a cavalry tagma.
Drungary/Drungarios - Leader of an infantry drungus.
Moirarch - Leader of a cavalry moira.
Merarch - Leader of a cavalry meros.
Turmarch/Tourmarch - Leader of an infantry turma.
Strategos - General in charge of a Themata (Theme)
Ourghos - Lance Corporal
Lochaghos - Warrant Officer. A Lochaghos commanded the Lochaghiai. The Lochagos was assisted in his mission by his second in command the Dekarchos.
Ilarch/Illarch - The senior Hekatonarch
Stratopedarches (Master of the Camp) - This official was in charge of making sure the army was stocked with food and arms.
Hoplitarches/Archegetes - Commander of all infantry in a large army.
Ethnarches - The ethnarch, commander of foreign troops.
Kontostaulos - Greek form of Latin Comes stabuli ‘count of the stable’ and various European feudal titles such as English "constable" - the chief of the Frankish mercenaries.
Hetaireiarches - The chief of the barbarian mercenaries, the Hetaireia, successor to the Foederati. Initially subdivided into Greater (Megale), Middle (Mese) and Little (Mikra) Hetaireia.
Akolouthos - "Acolyte," the chief of the Varangian Guard during the Palaeologan era.
Manglavitai - A category of palace guards, armed with sword and whip (manglavion, from the Arabic mijlab). Under the command of a Protomanglavites.
Topoteretes - Meaning "place-holder", "lieutenant". Found at various levels of the hierarchy, as deputies to commanders of the imperial tagmata, deputy to a drungarios.
Chartoularios - Secretary.
Protomandator - Head messenger.
Bandophoroi - Standard bearers, of which there are about 40 per chiliarchy.
Mandatores - Messengers, of which there are about 40 per chiliarchy.
UNIT SIZE APPROXIMATIONS
The unit types listed will have the infantry title listed first, and the cavalry title (if different) listed after the slash. The english approximation will be in paranthesis where applicable.
Rearguard - A unit of four soldiers, commanded by a Tetrarch.
Vanguard - A unit of five troops, led by a Pentarch.
Decarchy or Decad/Dekarkia (Squad) - A unit of ten soldiers. Composed of one Rear Guard and one Vanguard and commanded by a Decarch.
Allaghia (Platoon) - A unit of fifty troops, comprised of ten squads and commanded by a Pentecontarch.
Kentarchia/Hekatontarchia (Century) - A unit of one hundred soldiers, composed of two platoons and led by a Kentarch/Hekatontarch.
Banda (Squadron) - A cavalry-only unit composed of 200-400 troops, made up of two to four centuries and commanded by a Komes.
Numeri (Company) - A rarely used infantry-only unit composed of 300-400 soldiers, being three to four centuries led by a Topoteretes.
Chiliarchy/Tagma (Battalion) - A unit composed of several Numeri/Banda, up to roughly 1000 troops, commanded by a Chiliarch/Domestikos.
Drungus or Drungoi/Mora(i) (Brigade) - A unit composed of roughly two to four battalions, with 2000-4000 soldiers, led by a Drungary/Moirarch.
Turma/Meros (Division) - A unit composed of two to four brigades, with 4000-16,000 troops, commanded by a Merarch/Turmarch.
Themata (Army) - This unit size is generally composed of both infantry and cavalry units, usually comprised by four divisions for 16,000-64,000 (or more) soldiers, commanded by a Strategos.