HST 236 – The Strength and Size of the Roman Army.
Josh Davey - jdavey1@sheffield.ac.uk
The Size of the Roman Army.
Background of the Army during the early empire. 753 – 31 BC.
Roman Army during the foundation of Rome in the Regal Period – As detailed in Livy’s Ab Urbe Condita (History of Rome) and Plutarch’s Life of Romulus, that the original Roman legion, established by
Romulus, is said to have comprised of some 3000 soldiers and 300 cavalry. This small number would safeguard the roman legion until the union with the Sabines expanded the city – doubling the size of
the Roman army. Towards the end of the Regal period, by the time of the Tarquini (Lucius) the army had expanded to a size of some 18,000 men – an exponential increase from the beginnings of the
Roman legion.
The republican period – The Latin War. During the Latin War there were two enlisted Roman armies, both comprising of two legions of some 4,000 – 5,000 men and 300 - 400 cavalry each. Thus, during
this period the total force amassed to approximately 20,000 mobilised men and 1,600 cavalry. The Socii Latini, translates to ‘Latin allies’, and although the vast majority were not of Latin tribes, they
instead were part of autonomous tribes of the Italian Peninsula and were in permanent military alliance with the Roman Republic, in exchange for permanent Roman citizenship and goods. They were
allied until the Social War of 91-88 BCE, when the Picentes initiated an all-out conflict against the empire in response to denied citizenship requests. The Socii during their tenure as allies were, as a
collective, a powerful force consisting of some 20,000 men and almost 4,000 cavalry (four times the cavalry power of the Roman empire.)
Pyrrhic War – Roman field Army, according to Livy, consisted of four Armies each containing two Roman legions and two ally units – all some 4,000 – 5,000 men in strength with 300 cavalry to each
Roman Unit and three times as many cavalry to an ally unit, amassing to a total of approximately 80,000 men and 10,000 on horseback.
First and Second Punic Wars
Middle of the third century BC - the Roman army consisted occupation forces in both Sicily and Tarentum, comprised of two legions of approximately 4,000 men and 300 cavalry each), two consular
armies (of two reinforced legions of approximately 5,000 men and 300 cavalry each) and about 30,000 allied soldiers (including 2,000 cavalry). All of which were mobilised and in permanent active
service, with another 90,000 men in reserve, ready if necessary. Thus, the Roman Army, was believed to be at a size of some 150,000 men during the mid-third century.
As the Republican period draws to an end the Roman Army has exponentially grown in size, beginning the shift in military power and size necessary to transform Rome from a Republic to an Empire.
Lawrence Keppie ‘The Making of the Roman Empire’, states that at the death of Julius Caesar there were 37 legions in the Roman world. Keppie also goes on to emphasise how extremely mobile these
units were adding to the growing power of the Empire.
The Roman Army in the High Empire 31 BC – AD 284: In Yann Le Bohec’s recent study it is believed the legionary forces may have reached some 125,000 men, divided into 25 legions, with additional
auxiliary forces totalling 250,000 soldiers including 30,000 cavalry. There were also some 10,000 soldiers stationed in the capital, including the Praetorian guard, Urban cohorts, Vigiles, and equites
singulares Augusti. Paul Holder's 2003 study within ‘The Roman Army in Britain’ broadly affirms these figures, finding that the Roman army consisted of approximately 380,000 soldiers of which 155,000
were legionaries and 225,000 were auxiliaries. Adrian Goldsworthy states that by the time of Severus the Roman army reached around 500,000 total individuals, with 33 legions: 5,500 men in each.
Late Roman Empire 284 – 337.
The introduction of the tetrarchy by Diocletian brought the number of Roman legions to between 53 and 56 in AD 300. The garrison of Rome also underwent crucial mass expansion totalling around
24,000 men stationed to protect the Roman capital and its bureaucratic system in the face of rising usurper attack threats. John Lydus a Roman bureaucrat details that during Justinian’s period the
Roman fleet numbered some 45,000. Constantine’s ascension to the throne saw the revival of dynastic monarchy and for the final time, with the size of the Imperial Roman Army Increasing: with the
number of legions rising to between 64 and 67 in 337 at the time of Constantine’s death. To the reverse a table detailing the scholarly estimates of the number of soldiers of the first three centuries of
the Roman empire can be found.
HST 236 – The Strength and Size of the Roman Army.
Josh Davey - jdavey1@sheffield.ac.uk