The (; , though sometimes referred to as "knights" in English) constituted the second of the property/social-based classes of ancient Rome, ranking below the senatorial class. A member of the equestrian order was known as an ().
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 (hundreds) of cavalry (300 horses for each consular legion). Around 400BC, 12 more of cavalry were established and these included non-patricians (plebeians). 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 . 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 (218–202 BC), all the members of the first class of commoners were required to serve as cavalrymen. The presence of in the Roman cavalry diminished steadily in the period 200–88 BC as only could serve as the army's senior officers; as the number of legions proliferated fewer were available for ordinary cavalry service. After 88 BC, were no longer drafted into the legionary cavalry, although they remained technically liable to such service throughout the Principate era (to 284 AD). They continued to supply the senior officers of the army throughout the Principate.
With the exception of the purely hereditary patricians, the 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 (every five years) 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 and was doubled to 100,000 by the emperor Augustus (sole rule 30 BC – 14 AD) – 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.
Under Augustus, the senatorial elite was given formal status (as the ) with a higher wealth threshold (250,000 , or the pay of 1,100 legionaries) and superior rank and privileges to ordinary . During the Principate, filled the senior administrative and military posts of the imperial government. There was a clear division between jobs reserved for senators (the most senior) and those reserved for non-senatorial . 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 (normally a decade) of military service as a senior army officer, followed by senior administrative or military posts in the provinces. Senators and 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 who had earned their membership by distinguished military service, often rising from the ranks: career military officers from the provinces (especially the Balkan provinces) who displaced the Italian aristocrats in the top military posts, and under Diocletian (ruled 284–305) 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 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 (as opposed to a number of separate hilltop settlements) until .
Roman tradition relates that the Order of Knights was founded by Romulus, who supposedly established a cavalry regiment of 300 men called the ("Swift Squadron") to act as his personal escort, with each of the three Roman "tribes" (actually voting constituencies) supplying 100 horses. This cavalry regiment was supposedly doubled in size to 600 men by King Lucius Tarquinius Priscus (traditional dates 616–578 BC). That the cavalry was increased to 600 during the regal era is plausible, as in the early republic the cavalry fielded remained 600-strong (two legions with 300 horses each). However, according to Livy, King Servius Tullius (traditional reign-dates 578–535 BC) established a further 12 centuriae of equites, a further tripling of the cavalry. Yet this was 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.
Theodor Mommsen argues that the royal cavalry was drawn exclusively from the ranks of the patricians (patricii), 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 (voting constituencies) of equites in the comitia centuriata (electoral assembly) 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 (and therefore hereditary) in the regal period. (However, Cornell considers the evidence tenuous).
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. The position and powers of a Roman king were thus similar to those of Julius Caesar when he was appointed dictator-for-life in 44 BC. That was why Caesar's assassin, Marcus Junius Brutus, felt a moral obligation to emulate his claimed ancestor, Lucius Junius Brutus, "the Liberator", the man who, Roman tradition averred, in 509 BC, led the coup that overthrew the last king, Tarquin the Proud, and established the republic. 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 (later called "consuls"), 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 (in 406 BC).
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 (in contrast to equites equo publico). However, due to a lack of evidence, the origins and definition of equo privato equites remain obscure.
It is widely agreed that the twelve 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 (clans) recorded, whereas just 14 remained at the time of Julius Caesar (dictator of Rome 48–44 BC), whose own Iulii clan was patrician.
In contrast, the ranks of equites, although also hereditary (in the male line), 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 (Leader of the Senate), 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 (340–338 BC) and of the Samnite Wars (343–290) 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 gruelling 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.