Equites


The equites constituted the second of the property-based classes of ancient Rome, ranking below the senatorial class. A member of the equestrian order was known as an eques.

Description

During the Roman kingdom and the first century of the Roman Republic, legionary cavalry was recruited exclusively from the ranks of the patricians, who were expected to provide six centuriae of cavalry. Around 400BC, 12 more centuriae of cavalry were established and these included non-patricians. Around 300 BC the Samnite Wars obliged Rome to double the normal annual military levy from two to four legions, doubling the cavalry levy from 600 to 1,200 horses. Legionary cavalry started to recruit wealthier citizens from outside the 18 centuriae. These new recruits came from the first class of commoners in the Centuriate Assembly organisation and were not granted the same privileges.
By the time of the Second Punic War, all the members of the first class of commoners were required to serve as cavalrymen. The presence of equites in the Roman cavalry diminished steadily in the period 200–88 BC as only equites could serve as the army's senior officers; as the number of legions proliferated fewer were available for ordinary cavalry service. After c. 88 BC, equites were no longer drafted into the legionary cavalry, although they remained technically liable to such service throughout the principate era. They continued to supply the senior officers of the army throughout the principate.
With the exception of the purely hereditary patricians, the equites were originally defined by a property threshold. The rank was passed from father to son, although members of the order who at the regular quinquennial census no longer met the property requirement were usually removed from the order's rolls by the Roman censors. In the late republic, the property threshold stood at 50,000 denarii and was doubled to 100,000 by the emperor Augustus – roughly the equivalent to the annual salaries of 450 contemporary legionaries.
In the later republican period, Roman senators and their offspring became an unofficial elite within the equestrian order. As senators' abilities to engage in commerce was strictly limited by law, the bulk of non-agricultural activities were in the hands of non-senatorial equites. As well as holding large landed estates, equites came to dominate mining, shipping and manufacturing industry. In particular, tax farming companies were almost all in the hands of equites.
Under Augustus, the senatorial elite was given formal status with a higher wealth threshold and superior rank and privileges to ordinary equites. During the principate, equites filled the senior administrative and military posts of the imperial government. There was a clear division between jobs reserved for senators and those reserved for non-senatorial equites. But the career structure of both groups was broadly similar: a period of junior administrative posts in Rome or Roman Italy, followed by a period of military service as a senior army officer, followed by senior administrative or military posts in the provinces. Senators and equites formed a tiny elite of under 10,000 members who monopolised political, military and economic power in an empire of about 60 million inhabitants.
During the 3rd century AD, power shifted from the Italian aristocracy to a class of equites who had earned their membership by distinguished military service, often rising from the ranks: career military officers from the provinces who displaced the Italian aristocrats in the top military posts, and under Diocletian from the top civilian positions also. This effectively reduced the Italian aristocracy to an idle, but immensely wealthy, group of landowners. During the 4th century, the status of equites was debased to insignificance by excessive grants of the rank. At the same time the ranks of senators were swollen to over 4,000 by the establishment of the Byzantine Senate, a second senate in Constantinople and the tripling of the membership of both senates. The senatorial order of the 4th century was thus the equivalent of the equestrian order of the principate.

Regal era (753–509 BC)

According to Roman legend, Rome was founded by its first king, Romulus, in 753 BC. However, archaeological evidence suggests that Rome did not acquire the character of a unified city-state until ca. 625BC.
Roman tradition relates that the Order of Knights was founded by Romulus, who supposedly established a cavalry regiment of 300 men called the Celeres to act as his personal escort, with each of the three Roman "tribes" supplying 100 horses. This cavalry regiment was supposedly doubled in size to 600 men by King Lucius Tarquinius Priscus. That the cavalry was increased to 600 during the regal era is plausible, as in the early republic the cavalry fielded remained 600-strong. However, according to Livy, King Servius Tullius established a further 12 centuriae of equites, a further tripling of the cavalry. But this is probably anachronistic, as it would have resulted in a contingent of 1,800 horse, incongruously large, compared to the heavy infantry, which was probably only 6,000 strong in the late regal period. Instead, the additional 12 centuriae were probably created at a later stage, perhaps around 400 BC, but these new units were political not military, most likely designed to admit plebeians to the Order of Knights.
Apparently, equites were originally provided with a sum of money by the state to purchase a horse for military service and for its fodder. This was known as an equus publicus.
Mommsen argues that the royal cavalry was drawn exclusively from the ranks of the patricians, the aristocracy of early Rome, which was purely hereditary. Apart from the traditional association of the aristocracy with horsemanship, the evidence for this view is the fact that, during the republic, six centuriae of equites in the comitia centuriata retained the names of the original six royal cavalry centuriae. These are very likely the "centuriae of patrician nobles" in the comitia mentioned by the lexicologist Sextus Pompeius Festus. If this view is correct, it implies that the cavalry was exclusively patrician in the regal period..

Early republic (509–338 BC)

It is widely accepted that the Roman monarchy was overthrown by a patrician coup, probably provoked by the Tarquin dynasty's populist policies in favour of the plebeian class. Alfoldi suggests that the coup was carried out by the celeres themselves. According to the Fraccaro interpretation, when the Roman monarchy was replaced with two annually elected praetores, the royal army was divided equally between them for campaigning purposes, which, if true, explains why Polybius later said that a legion's cavalry contingent was 300 strong.
The 12 additional centuriae ascribed by Livy to Servius Tullius were, in reality, probably formed around 400 BC. In 403 BC, according to Livy, in a crisis during the siege of Veii, the army urgently needed to deploy more cavalry, and "those who possessed equestrian rating but had not yet been assigned public horses" volunteered to pay for their horses out of their own pockets. By way of compensation, pay was introduced for cavalry service, as it had already been for the infantry.
The persons referred to in this passage were probably members of the 12 new centuriae who were entitled to public horses, but temporarily waived that privilege. Mommsen, however, argues that the passage refers to members of the first class of commoners being admitted to cavalry service in 403 BC for the first time as an emergency measure. If so, this group may be the original so-called equites equo privato, a rank that is attested throughout the history of the republic. However, due to a lack of evidence, the origins and definition of equo privato equites remain obscure.
It is widely agreed that the 12 new centuriae were open to non-patricians. Thus, from this date if not earlier, not all equites were patricians. The patricians, as a closed hereditary caste, steadily diminished in numbers over the centuries, as families died out. Around 450 BC, there are some 50 patrician gentes recorded, whereas just 14 remained at the time of Julius Caesar, whose own Iulii clan was patrician.
In contrast, the ranks of equites, although also hereditary, were open to new entrants who met the property requirement and who satisfied the Roman censors that they were suitable for membership. As a consequence, patricians rapidly became only a small minority of the equestrian order. However, patricians retained political influence greatly out of proportion with their numbers. Until 172 BC, one of the two consuls elected each year had to be a patrician.
In addition, patricians may have retained their original six centuriae, which gave them a third of the total voting-power of the equites, even though they constituted only a tiny minority of the order by 200 BC. Patricians also enjoyed official precedence, such as the right to speak first in senatorial debates, which were initiated by the princeps senatus, a position reserved for patricians. In addition, patricians monopolized certain priesthoods and continued to enjoy enormous prestige.

Later republic (338–30 BC)

Transformation of state and army (338–290)

The period following the end of the Latin War and of the Samnite Wars saw the transformation of the Roman Republic from a powerful but beleaguered city-state into the hegemonic power of the Italian peninsula. This was accompanied by profound changes in its constitution and army. Internally, the critical development was the emergence of the senate as the all-powerful organ of state.
By 280 BC, the senate had assumed total control of state taxation, expenditure, declarations of war, treaties, raising of legions, establishing colonies and religious affairs. In other words, of virtually all political power. From an ad hoc group of advisors appointed by the consuls, the senate had become a permanent body of around 300 life peers who, as largely former Roman magistrates, boasted enormous experience and influence. At the same time, the political unification of the Latin nation, under Roman rule after 338 BC, gave Rome a populous regional base from which to launch its wars of aggression against its neighbours.
The grueling contest for Italian hegemony that Rome fought against the Samnite League led to the transformation of the Roman army from the Greek-style hoplite phalanx that it was in the early period, to the Italian-style manipular army described by Polybius. It is believed that the Romans copied the manipular structure from their enemies the Samnites, learning through hard experience its greater flexibility and effectiveness in the mountainous terrain of central Italy.
It is also from this period that every Roman army that took the field was regularly accompanied by at least as many troops supplied by the socii. Each legion would be matched by a confederate ala, a formation that contained roughly the same number of infantry as a legion, but three times the number of horses.
Legionary cavalry also probably underwent a transformation during this period, from the light, unarmoured horsemen of the early period to the Greek-style armoured cuirassiers described by Polybius. As a result of the demands of the Samnite hostilities, a normal consular army was doubled in size to two legions, making four legions raised annually overall. Roman cavalry in the field thus increased to approximately 1,200 horses.
This now represented only 25% of the army's total cavalry contingent, the rest being supplied by the Italian confederates. A legion's modest cavalry share of 7% of its 4,500 total strength was thus increased to 12% in a confederate army, comparable with any other forces in Italy except the Gauls and also similar to those in Greek armies such as Pyrrhus's.

Political role

Despite an ostensibly democratic constitution based on the sovereignty of the people, the Roman Republic was in reality a classic oligarchy, in which political power was monopolised by the richest social echelon. Probably by 300 BC, the centuriate organisation of the Roman citizen body for political purposes achieved the evolved form described by Polybius and Livy. The comitia centuriata was the most powerful people's assembly, as it promulgated Roman laws and annually elected the Roman magistrates, the executive officers of the state: consuls, praetors, aediles and quaestors.
In the assembly, the citizen body was divided into 193 centuriae, or voting constituencies. Of these, 18 were allocated to equites and a further 80 to the first class of commoners, securing an absolute majority of the votes for the wealthiest echelon of society, although it constituted only a small minority of the citizenry..
As a result, the wealthiest echelon could ensure that the elected magistrates were always their own members. In turn, this ensured that the senate was dominated by the wealthy classes, as its membership was composed almost entirely of current and former magistrates.

Military officer role

In the "polybian" army of the mid-republic, equites held the exclusive right to serve as senior officers of the army. These were the six tribuni militum in each legion who were elected by the comitia at the start of each campaigning season and took turns to command the legion in pairs; the praefecti sociorum, commanders of the Italian confederate alae, who were appointed by the consuls; and the three decurions that led each squadron of legionary cavalry.

Cavalry role

As their name implies, equites were liable to cavalry service in the legion of the mid-republic. They originally provided a legion's entire cavalry contingent, although from an early stage, when equestrian numbers had become insufficient, large numbers of young men from the first class of commoners were regularly volunteering for the service, which was considered more glamorous than the infantry.
The cavalry role of equites dwindled after the Second Punic War, as the number of equestrians became insufficient to provide the senior officers of the army and general cavalrymen as well. Equites became exclusively an officer-class, with the first class of commoners providing the legionary cavalry.

Ethos

From the earliest times and throughout the Republican period, Roman equites subscribed, in their role as Roman cavalrymen, to an ethos of personal heroism and glory. This was motivated by the desire to justify their privileged status to the lower classes that provided the infantry ranks, to enhance the renown of their family name, and to augment their chances of subsequent political advancement in a martial society. For equites, a focus of the heroic ethos was the quest for spolia militaria, the stripped armour and weapons of a foe whom they had killed in single combat. There are many recorded instances. For example, Servilius Geminus Pulex, who went on to become Consul in 202 BC, was reputed to have gained spolia 23 times.
The higher the rank of the opponent killed in combat, the more prestigious the spolia, and none more so than spolia duci hostium detracta, spoils taken from an enemy leader himself. Many equites attempted to gain such an honour, but very few succeeded for the reason that enemy leaders were always surrounded by large numbers of elite bodyguards.
One successful attempt, but with a tragic twist, was that of the decurion Titus Manlius Torquatus in 340 BC during the Latin War. Despite strict orders from the consuls not to engage the enemy, Manlius could not resist accepting a personal challenge from the commander of the Tusculan cavalry, which his squadron encountered while on reconnaissance. There ensued a fiercely contested joust with the opposing squadrons as spectators. Manlius won, spearing his adversary after the latter was thrown by his horse. But when the triumphant young man presented the spoils to his father, the latter ordered his son's immediate execution for disobeying orders. "Orders of Manlius" became a proverbial army term for orders that must on no account be disregarded.

Business activities

In 218 BC, the lex Claudia restricted the commercial activity of senators and their sons, on the grounds that it was incompatible with their status. Senators were prohibited from owning ships of greater capacity than 300 amphorae - this being judged sufficient to carry the produce of their own landed estates but too small to conduct large-scale sea transportation.
From this time onwards, senatorial families mostly invested their capital in land. All other equestrians remained free to invest their wealth, greatly increased by the growth of Rome's overseas empire after the Second Punic War, in large-scale commercial enterprises including mining and industry, as well as land. Equestrians became especially prominent in tax farming and, by 100 BC, owned virtually all tax-farming companies.
During the late republican era, the collection of most taxes was contracted out to private individuals or companies by competitive tender, with the contract for each province awarded to the publicanus who bid the highest advance to the state treasury on the estimated tax-take of the province. The publicanus would then attempt to recoup his advance, with the right to retain any surplus collected as his profit. This system frequently resulted in extortion from the common people of the provinces, as unscrupulous publicani often sought to maximise their profit by demanding a much higher rates of tax than originally set by the government. The provincial governors whose duty it was to curb illegal demands were often bribed into acquiescence by the publicani.
The system also led to political conflict between equites publicani and the majority of their fellow-equites, especially senators, who as large landowners wanted to minimise the tax on land outside Italy, which was the main source of state revenue. This system was terminated by the first Roman emperor, Augustus, who transferred responsibility for tax collection from the publicani to provincial local authorities. Although the latter also frequently employed private companies to collect their tax quotas, it was in their own interests to curb extortion. During the imperial era, tax collectors were generally paid an agreed percentage of the amount collected. equites publicani'' became prominent in banking activities such as money-lending and money-changing.

Privileges

The official dress of equestrians was the tunica angusticlavia, worn underneath the toga, in such a manner that the stripe over the right shoulder was visible equites bore the title eques Romanus, were entitled to wear an anulus aureus on their left hand, and, from 67 BC, enjoyed privileged seats at games and public functions.

Augustan equestrian order (Principate era)

Differentiation of the senatorial order

The senate as a body was formed of sitting senators, whose number was held at around 600 by the founder of the principate, Augustus and his successors until 312. Senators' sons and further descendants technically retained equestrian rank unless and until they won a seat in the senate. But Talbert argues that Augustus established the existing senatorial elite as a separate and superior order to the equites for the first time. The evidence for this includes:
A family's senatorial status depended not only on continuing to match the higher wealth qualification, but on their leading member holding a seat in the senate. Failing either condition, the family would revert to ordinary knightly status. Although sons of sitting senators frequently won seats in the senate, this was by no means guaranteed, as candidates often outnumbered the 20 seats available each year, leading to intense competition.

''Ordo equester'' under Augustus

As regards the equestrian order, Augustus apparently abolished the rank of equo privato, according all its members equo publico status. In addition, Augustus organised the order in a quasi-military fashion, with members enrolled into six turmae. The order's governing body were the seviri, composed of the "commanders" of the turmae. In an attempt to foster the equites esprit de corps, Augustus revived a defunct republican ceremony, the recognitio equitum, in which equites paraded every five years with their horses before the consuls. At some stage during the early principate, equites acquired the right to the title "egregius".
Beyond equites with equus publicus, Augustus' legislation permitted any Roman citizen who was assessed in an official census as meeting the property requirement of 100,000 denarii to use the title of eques and wear the narrow-striped tunic and gold ring. But such "property-qualified equites" were not apparently admitted to the ordo equester itself, but simply enjoyed equestrian status.
Only those granted an equus publicus by the emperor were enrolled in the order. Imperial equites were thus divided into two tiers: a few thousand mainly Italian equites equo publico, members of the order eligible to hold the public offices reserved for the equites; and a much larger group of wealthy Italians and provincials of equestrian status but outside the order.
Equestrians could in turn be elevated to senatorial rank, but in practice this was much more difficult than elevation from commoner to equestrian rank. To join the upper order, not only was the candidate required to meet the minimum property requirement of 250,000 denarii, but also had to be elected a member of the senate. There were two routes for this, both controlled by the emperor:
In public service, equites equo publico had their own version of the senatorial cursus honorum, or conventional career-path, which typically combined military and administrative posts. After an initial period of a few years in local government in their home regions as administrators or as priests, equites were required to serve as military officers for about 10 years before they would be appointed to senior administrative or military posts.
, a town in Latium, then served as a military officer, first as praefectus of cohors I Montanorum, then tribunus militum of legio II Augusta, and finally praefectus of ala veterana Gallorum. Then, after a stint as subpraefectus classis of the imperial fleet at Ravenna, Sabinus was governor of the Alpes Poeninae and then of Dacia Apulensis provinces. His son, who erected the memorial, is described as of equo publico rank. Dated to the early Severan period.
Equestrians exclusively provided the praefecti of the imperial army's auxiliary regiments and five of the six tribuni militum in each legion. The standard equestrian officer progression was known as the "tres militiae" : praefectus of a cohors, followed by tribunus militum in a legion, and finally praefectus of an ala. From the time of Hadrian, a fourth militia was added for exceptionally gifted officers, commander of an ala milliaria. Each post was held for three to four years.
Most of the top posts in the imperial administration were reserved for senators, who provided the governors of the larger provinces, the legati legionis of all legions outside Egypt, and the praefectus urbi, who controlled the Cohortes Urbanae, the only fully armed force in the city apart from the Praetorian Guard. Nevertheless, a wide range of senior administrative and military posts were created and reserved for equestrians by Augustus, though most ranked below the senatorial posts.
In the imperial administration, equestrian posts included that of the governorship of the province of Egypt, which was considered the most prestigious of all the posts open to equites, often the culmination of a long and distinguished career serving the state. In addition, equites were appointed to the governorship of some smaller provinces and sub-provinces e.g. Judaea, whose governor was subordinate to the governor of Syria.
Equestrians were also the chief financial officers of the imperial provinces, and the deputy financial officers of senatorial provinces. At Rome, equestrians filled numerous senior administrative posts such as the emperor's secretaries of state and the praefecti annonae.
In the military, equestrians provided the praefecti praetorio who also acted as the emperor's chiefs of military staff. There were normally two of these, but at times irregular appointments resulted in just a single incumbent or even three at the same time. Equestrians also provided the praefecti classis of the two main imperial fleets at Misenum in the bay of Naples and at Ravenna on the Italian Adriatic coast. The command of Rome's fire brigade and minor constabulary, the vigiles, was likewise reserved for equites.
Not all equites followed the conventional career-path. Those equestrians who specialised in a legal or administrative career, providing judges in Rome's law courts and state secretaries in the imperial government, were granted dispensation from military service by Emperor Hadrian. At the same time, many equites became career military officers, remaining in the army for much longer than 10 years. After completing their tres militiae, some would continue to command auxiliary regiments, moving across units and provinces.
Already wealthy to start with, equites equo publico accumulated even greater riches through holding their reserved senior posts in the administration, which carried enormous salaries. For example, the salaries of equestrian procuratores ranged from 15,000 to a maximum of 75,000 denarii per annum, whilst an equestrian praefectus of an auxiliary cohort was paid about 50 times as much as a common foot soldier. A praefectus could thus earn in one year the same as two of his auxiliary rankers combined earned during their entire 25-year service terms.

Relations with the emperor

It was suggested by ancient writers, and accepted by many modern historians, that Roman emperors trusted equestrians more than men of senatorial rank, and used the former as a political counterweight to the senators. According to this view, senators were often regarded as potentially less loyal and honest by the emperor, as they could become powerful enough, through the command of provincial legions, to launch coups.
They also had greater opportunities for peculation as provincial governors. Hence the appointment of equestrians to the most sensitive military commands. In Egypt, which supplied much of Italy's grain needs, the governor and the commanders of both provincial legions were drawn from the equestrian order, since placing a senator in a position to starve Italy was considered too risky.
The commanders of the Praetorian Guard, the principal military force close to the emperor at Rome, were also usually drawn from the equestrian order. Also cited in support of this view is the appointment of equestrian fiscal procuratores, reporting direct to the emperor, alongside senatorial provincial governors. These would supervise the collection of taxes and act as watchdogs to limit opportunities for corruption by the governors.
According to Talbert, however, the evidence suggests that equites were no more loyal or less corrupt than senators. For example, c. 26 BC, the equestrian governor of Egypt, Cornelius Gallus, was recalled for politically suspect behaviour and sundry other misdemeanours. His conduct was deemed sufficiently serious by the senate to warrant the maximum penalty of exile and confiscation of assets. Under Tiberius, both the senatorial governor and the equestrian fiscal procurator of Asia province were convicted of corruption.
There is evidence that emperors were as wary of powerful equites as they were of senators. Augustus enforced a tacit rule that senators and prominent equestrians must obtain his express permission to enter the province of Egypt, a policy that was continued by his successors. Also, the command of the Praetorian Guard was normally split between two equites, to reduce the potential for a successful coup d'état. At the same time, command of the second military force in Rome, the cohortes urbanae, was entrusted to a senator.

Oligarchical rule in the early ''principate'' (to AD 197)

Because the senate was limited to 600 members, equites equo publico, numbering several thousands, greatly outnumbered men of senatorial rank. Even so, senators and equites combined constituted a tiny elite in a citizen-body of about 6 million and an empire with a total population of 60–70 million. This immensely wealthy elite monopolised political, military and economic power in the empire. It controlled the major offices of state, command of all military units, ownership of a significant proportion of the empire's arable land and of most major commercial enterprises.
Overall, senators and equites cooperated smoothly in the running of the empire. In contrast to the chaotic civil wars of the late republic, the rule of this tiny oligarchy achieved a remarkable degree of political stability. In the first 250 years of the principate, there was only a single episode of major internal strife: the civil war of 68–69.

Equestrian hierarchy

It seems that from the start the equestrians in the imperial service were organised on a hierarchical basis reflecting their pay-grades. According to Suetonius, writing in the early part of the second century AD, the equestrian procurators who "performed various administrative duties throughout the empire" were from the time of Emperor Claudius I organised into four pay-grades, the trecenarii the ducenarii, the centenarii, and the sexagenarii, receiving 300,000, 200,000, 100,000, and 60,000 sesterces per annum respectively. Cassius Dio, writing a century later, attributed the beginnings of this process to the first emperor, Augustus, himself.
There is almost no literary or epigraphic evidence for the use of these ranks until towards the end of the 2nd century. However, it would seem that the increasing employment of equestrians by the emperors in civil and military roles had had social ramifications for it is then that there begin to appear the first references to a more far-reaching hierarchy with three distinct classes covering the whole of the order: the Viri Egregii ; the Viri Perfectissimi ; and the Viri Eminentissimi. The mechanisms by which the equestrians were organised into these classes and the distinctions enforced is not known. However, it is generally assumed that the highest class, the Viri Eminentissimi, was confined to the Praetorian Prefects, while the Viri Perfectissimi were the heads of the main departments of state, and the great prefectures, including Egypt, the city watch, the corn supply etc. and men commissioned to carry out specific tasks by the emperor himself such as the military duces. The defining characteristic of the perfectissimate seems to have been that its members were of or associated socially with the imperial court circle and were office-holders known to the emperor and appointed by his favour. It is also possible that system was intended to indicate the hierarchy of office-holders in situations where this might be disputed. The Viri Egregii comprehended the rest of the Equestrian Order, in the service of the emperors.
The Viri Egregii included officials of all four pay-grades. Ducenariate procurators governing provinces not reserved for senators were of this category as were the praefecti legionum, after Gallienus opened all legionary commands to equestrians. However, it seems that after 270 AD the procuratores ducenarii were elevated into the ranks of the Viri Perfectissimi.

Equestrians in the later empire (AD 197–395)

Rise of the military equestrians (3rd century)

The 3rd century saw two major trends in the development of the Roman aristocracy: the gradual takeover of the top positions in the empire's administration and army by military equestrians and the concomitant exclusion of the Italian aristocracy, both senators and equites and the growth in hierarchy within the aristocratic orders.
Augustus instituted a policy, followed by his successors, of elevating to the ordo equester the primus pilus of each legion, at the end of his single year in the post. This resulted in about 30 career-soldiers, often risen from the ranks, joining the order every year. These equites primipilares and their descendants formed a section of the order that was quite distinct from the Italian aristocrats who had become nearly indistinguishable from their senatorial counterparts.
They were almost entirely provincials, especially from the Danube provinces where about half the Roman army was deployed. These Danubians mostly came from Pannonia, Moesia, Thrace, Illyria and Dalmatia. They were generally far less wealthy than the landowning Italians and they rarely held non-military posts.
Their professionalism led emperors to rely on them ever more heavily, especially in difficult conflicts such as the Marcomannic Wars. But because they were only equestrians, they could not be appointed to the top military commands, those of legatus Augusti pro praetore and legatus legionis. In the later 2nd century, emperors tried to circumvent the problem by elevating large numbers of primipilares to senatorial rank by adlectio.
But this met resistance in the senate, so that in the 3rd century, emperors simply appointed equestrians directly to the top commands, under the fiction that they were only temporary substitutes. Septimius Severus appointed primipilares to command the three new legions that he raised in 197 for his Parthian War, Legio I, II & III Parthica Gallienus completed the process by appointing equites to command all the legions. These appointees were mostly provincial soldier-equestrians, not Italian aristocrats.
Under the reforming emperor Diocletian, himself an Illyrian equestrian officer, the military equestrian "takeover" was brought a stage further, with the removal of hereditary senators from most administrative, as well as military posts. Hereditary senators were limited to administrative jobs in Italy and a few neighbouring provinces, despite the fact that senior administrative posts had been greatly multiplied by the tripling of the number of provinces and the establishment of dioceses. The exclusion of the old Italian aristocracy, both senatorial and equestrian, from the political and military power that they had monopolised for many centuries was thus complete. The senate became politically insignificant, although it retained great prestige.
The 3rd and 4th centuries saw the proliferation of hierarchical ranks within the aristocratic orders, in line with the greater stratification of society as a whole, which became divided into two broad classes, with discriminatory rights and privileges: the honestiores and humiliores. Among the honestiores, equestrians were divided into five grades, depending on the salary-levels of the offices they held.
These ranged from egregii or sexagenarii to the eminentissimi, limited to the two commanders of the Praetorian Guard and, with the establishment of Diocletian's tetrarchy, the four praefecti praetorio that assisted the tetrarchs, each ruling over a quarter of the empire.

Idle aristocracy (4th century)

From the reign of Constantine I the Great onwards, there was an explosive increase in the membership of both aristocratic orders. Under Diocletian, the number of sitting members of the senate remained at around 600, the level it had retained for the whole duration of the principate. But Constantine established Byzantium as a twin capital of the empire, with its own senate, initially of 300 members. By 387, their number had swollen to 2,000, while the senate in Rome probably reached a comparable size, so that the upper order reached total numbers similar to the equo publico equites of the early principate. By this time, even some commanders of military regiments were accorded senatorial status.
At the same time the order of equites was also expanded vastly by the proliferation of public posts in the late empire, most of which were now filled by equestrians. The Principate had been a remarkably slim-line administration, with about 250 senior officials running the vast empire, relying on local government and private contractors to deliver the necessary taxes and services. During the 3rd century the imperial 'bureaucracy,' all officials and ranks expanded. By the time of the Notitia Dignitatum, dated to 395 A.D. comparable senior positions had grown to approximately 6,000, a 24-fold increase. The total number enrolled in the imperial civilian service, the militia inermata is estimated to have been 30-40,000: the service was professionalized with a staff made up almost entirely of free men on salary, and enrolled in a fictional legion, I Audiutrix.
In addition, large numbers of decuriones were granted equestrian rank, often obtaining it by bribery. Officials of ever lower rank were granted equestrian rank as reward for good service e.g. in 365, the actuarii of military regiments. This inflation in the number of equites inevitably led to the debasement of the order's prestige. By AD 400, equites were no longer an echelon of nobility, but just a title associated with mid-level administrative posts.
Constantine established a third order of nobility, the comites. This overlapped with senators and equites, drawing members from both. Originally, the comites were a highly exclusive group, comprising the most senior administrative and military officers, such as the commanders of the comitatus, or mobile field armies. But comites rapidly followed the same path as equites, being devalued by excessive grants until the title became meaningless by 450.
In the late 4th and in the 5th century, therefore, the senatorial class at Rome and Byzantium became the closest equivalent to the equo publico equestrian class of the early principate. It contained many ancient and illustrious families, some of whom claimed descent from the aristocracy of the republic, but had, as described, lost almost all political and military power. Nevertheless, senators retained great influence due to their enormous inherited wealth and their role as the guardians of Roman tradition and culture.
Centuries of capital accumulation, in the form of vast landed estates across many provinces resulted in enormous wealth for most senators. Many received annual rents in cash and in kind of over 5,000 lbs of gold, equivalent to 360,000 solidi, at a time when a miles would earn no more than four solidi a year in cash. Even senators of middling wealth could expect an income 1,000–1,500 lbs of gold.
The 4th-century historian Ammianus Marcellinus, a former high-ranking military staff officer who spent his retirement years in Rome, bitterly attacked the Italian aristocracy, denouncing their extravagant palaces, clothes, games and banquets and above all their lives of total idleness and frivolity. In his words can be heard the contempt for the senatorial class of a career soldier who had spent his lifetime defending the empire, a view clearly shared by Diocletian and his Illyrian successors. But it was the latter who reduced the aristocracy to that state, by displacing them from their traditional role of governing the empire and leading the army.

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Ancient

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