Diocletian Military Reform
Diocletian Military Reform
Diocletian Military Reform
Abstract. From among the many changes introduced by Diocletian, the military
reforms were the most important. We can even say that some other changes were
either direct or indirect results of this one. Of course, the introduction of the
taxation system capitatioiugatio was a result of the need to increase income
for growing expenses, from which the biggest one was the army. Even the Price
Edict as in the introductory part Diocletian and his co-regent admitted was a
result of concern for soldiers. The established measures of the military reforms
contributed to the stability of the state and mainly to the border protection of
the Empire by stopping barbarian attacks at least temporarily.
Good side of this reform was that the increased number of soldiers and the
better organisation increased the states defence power. Besides the larger
number of soldiers, expenses were raised by the fast development and by
cavalry participation, which involved much higher expenses than what was
needed for the infantry. Was the state able to provide the necessary funds
compared to those already existent, and if it was, for how long and in what
way? The military reforms could not give any more permanent result.
Another bad result was the decline in quality of the military personnel. The
recruiting system did not bring the best people into the legions. Probably
latifundium owners gave their worse workers to the army.
I. Problems
The army was the Empires protector from foreign enemies and internal rebellions as
well as the support of throne pretenders. The Empires military defence became the
rulers main duty and other things were under their control.1 That was probably
a reason for the introduction of new measures, the military reorganisation that
Diocletian dealt with, where major attention was paid to the border defense system.2
Military division into two parts by which the effectiveness of the army and
soldiers number increased was without doubt Diocletians innovation. According
to Rostovzeff: The military reform was the central preoccupation and it was
carried out in a few years, being nished by Constantine and his successors.3
A new problem was more powerful: latifundium owners (potentiores) and
their private army were not always loyal to the Emperor.
The role of the army increased especially during the period that preceded
Diocletians rule. That was a time when internal conicts and riots were common
and when barbarian attacks against the borders of the Empire were getting more
and more frequent and serious. Because of the throne conicts the borders were
often unprotected.
Army expenditures were huge. The garrisons existing in that time were strong
and were situated where the fortifying efforts were concentrated. During the time
when extensive works for the Pannonian strengthening were carried out, the nearby
smithery in Sisak (today a town in Serbia) had to work overtime.4 Having been a
decisive factor not only from the point of view of the Empires defence but also
from that of the seizure of the throne, the army had constantly increasing wages. In
183 A.D., Domitian increased the wages with one third, then Caracalla (211217)
added 70 million denarii to the military funds.5 All that together brought ination.
During the ghts for the throne and the military anarchy, additional income was
realised from robbery, and requisitions were made.
The great extent of attention that was paid to the army can be seen from the
fact that military bases had the same comforts that other towns had: aqueducts,
amphitheaters and public baths.6 Soldiers were judged in special courts that
were favouring them.7
Besides problems that affected all areas, certain problems affected only the army.
First of all, the discipline decreased; ofcers had to face several problems, such as
the diminished number of soldiers as well as their decreased willingness.
One defect of the army was the lack of mobility; the army became almost immobile
on the borders so mutual help was impossible. The fact that soldiers founded families
with neighbours from across the borders contributed to this. The once excellent
Roman roads got wasted during the economic crisis and increasing banditry. The
famous bandit, Bulla Felix with his men managed to maintain his positions for a
few years.8 Besides that, such improvised solutions added to the Empires lack of
defence, so barbarians and other rebelling people took advantage of that.
What signicance did the military have for Diocletian? According to the
majority of the authors, it can be seen among the principal motives of establishing
an edict and it was a protection from unscrupulous traders, about whom the
introductory part of the edict contains some data.
Besides the primary troops there were additional ones, which were added
to the legions. Legions did not exist in Rome and in Italy but Augustus formed
particular units: praetorian, civil and cohortes vigiles, whose task was the
Emperors personal security as well as protection from public rebellions.16
Praetorians had higher wages than common soldiers and even shorter serving
terms, which usually lasted from 25 to 30 years. Until the rule of Septimius
Severus, the Praetorian units consisted of Italians. After his death, the relation
between Italians and other nations drastically changed; Praetorians come from
other parts, especially from provinces along the Danube.17 The positions of the
legions and Praetorians became equal. Even during the following period, under
the rule of Diocletian, the role of the Praetorians was decisive in changing and
pronouncing the Emperors. The considerable participation of the Praetorians
in the politics of their times made some historians see it as a reason for the
Roman failure.18
Besides their regular duty, soldiers were involved even in public works.
Marcus Aurelius had some bridges built by his soldiers.19 Soldiers also inspected
the land and the Emperors military structure, too.20 Those duties were not the
only activities that soldiers had to undertake. They took part in the transportation
of grain by ships; worked in mines, prisons, paper factories as well as in river
guard. We are informed on all these operations from two papyri which contain
lists of soldier activity, being duty reports related to the Danube region.21
With the introduction of some innovations in the military eld, Alexander
Severus tried to strengthen the system but this contributed to the barbarisation
of the Roman army. His desire was to renew the Roman army, so he tried to form
one legion which would be composed only of Italians but, at the same time, it
consisted mostly of Illyrians.22 Besides that, his efforts to strengthen the cavalry
were quite clear; in order to achieve this he used Parthians, Alans and Goths.
This process aroused another new danger. It created the opportunity to have the
barbarised Roman army side with the barbarians, which happened later.
III. LimitaneiComitatenses
Diocletian was interested above all in border protection. During his rule, we can
talk about the development of a defence system, which meant that the borders
of the Empire were provided with levees, walls, fortresses and towers.23 On the
other hand, Constantine destroyed the defence system by removing the army
from the borders to towns.24
There are signicant archaeological and epigraphic proofs of the building of
strategic roads and of fortifying activity, the best ones are on the African, Syrian
and Arabian borders, while some investigations found fortications in the Rayne/
Rhine and Danube regions.25
Taking into consideration all troubles that an army had to face, in order to create
an appropriate mobile army, Diocletian reorganised the Roman army dividing it
into two parts, (groups) comitatenses and limitanei. According to Zosimus it
is sure that comitatenses as mobile forces were not the result of Constantines
merits,26 but the fact is that Constantine nished many things Diocletian started.
Comitatenses were mobile, terrain groups which were placed within the Empire.
They were located on strategically suitable spots, always behind the important
roads, which enabled an easy moving from one part of the state to another. In that
way it was possible to offer help whenever it was necessary. The soldiers were
younger men without families.
Another group, the limitanei, was formed as a border unit. These troops were
immobile and represented a kind of village border police.27 Their task was to
defend certain parts of the border. On border sections which were exposed to
frequent attacks, defensive fortications were built. This was the case with the
border that went down along the Danube, on present day Serbian territory. Roman
authorities started to build these fortications quite early, thus wall remainders
that divided Roman Britain from the barbarians, close to the AngloScottish
border, are visible even today. These fortications mark a turning point in Roman
history, a transition from offensive to defensive. Soldiers lived on the border area.
By cultivating that land they made a living for themselves and their families. The
land that was cultivated by border troop soldiers had a particular character.28
Thus the border defence system was created and given special attention.
The system of limes now changed and became a system of reasonably arranged
fortications and camps. The limes was in fact the border road, for the defence of
which they built a complicated system of ditches, trenches and fortresses.
Each of the above mentioned two groups took part in the defence of the Empire.
The army consisted of frontiersmen, who were interested in the protection of
their border section and at the same time by defending the borders from barbarian
attacks, they defended their properties and families. Even though this army did
not have the possibility to maneuver, they knew their territory and all of the
priorities arising from this were used in the best way. This part of the army quite
successfully managed to temporarily retain the enemy, until the arrival of the
mobile and strong comitatenses troops. Such a system was taken over by the
Byzantine Empire and adapted to its needs by creating the class of peasant
soldiers, called stratiotes.29
The military advantages of this system were various; it was quite a wise
action to use a considerable amount of untilled land along the borders and turn
it into cultivable areas. Besides that it reduced pressure on state funds there
was not enough money to pay the entire bureaucracy and the more and more
insatiable army.
With these measures, Diocletian improved the military situation in the Empire
and provided for its better defence.
One more important thing related to the army of this period was the military
profession as an obligation, a hereditary obligation of military service. It is not clear
when that obligation appeared. It seems that before Diocletian there must have been
some attempts of binding the soldiers to their profession. A general tendency of
binding people to their professions that started even before Diocletian, continued
during his rule, and what is quite clear, had an inuence on the soldiers.30 Soldiers
sons who were physically capable had to serve in the army just like their fathers; in
case of incapability, they were involved in curial service.31
There are some authors who nd a relation in respect of the military service
with Constantine the Great, who ruled after Diocletian.32 It is possible that even
before Diocletian there were some attempts to make military profession continual
and hereditary. It seems likely that Constantine, in the case of breaking military
prohibition regarding discharge, had to renew this order. But Diocletian made an
excellent move. He provided the army with land. Land usage was restricted to
military service, without formally binding soldiers to their profession. Not long
after, he introduced the heredity of military profession.
Although divided into two groups, it can be stated that according to its
structure, the army was a unitary body. Namely, the comitatenses as well as
the limitanei consisted of infantry and cavalry units. During this period the
role and signicance of the cavalry increased so we can rightfully talk about
there are some data about the number of the legions, not much is known about
the additional units.42
The data from Diocletians contemporaries about his army are quite
insufcient too. There are a few inscriptions on marble plaques and papyrus;
the size of the army can only be reconstructed through the analysis of a survived
list (Notitiae Dignitatum) made one century later.43 Any such data, however,
can be quite unreliable.
Authors who have dealt with this problem talk about an increased number of
soldiers.44 But there is some disagreement concerning the common legions and
the increased number of soldiers. Lactantius is of the opinion that the army of that
period was multiplied taking into consideration the fact that each tetrarch had
larger army than former principes had had.45 This claim probably goes too far. We
can hardly assume that the number of the troops was doubled, and it is even less
possible to have been four times larger. It would be hard to understand/believe
that a state, in times of demographic and economic decline, could organise an
army four times larger than in earlier times.
Some authors think that the number of legions was doubled to 68 during
the rule of Diocletian,46 while others talk about a huge increase mentioning 60
legions.47 Even though we can not nd out the correct number, it is quite clear
that the number of soldiers and that of legions was really increased. Judging by
some survived data, soldiers were mostly placed on the borders; everything was
still subordinated to border defence. Out of the 68 legions, 46 were placed on
the borders, 16 were used as local reserve, while 6 were the general strategic
reserves.48 Along the Danube, instead of the 11 legions, 16 were placed; in
Egypt there was only one but later on two more were added. Under the rule
of Severus there were 34 legions. Probably all, except for one or two, existed
before Diocletian succeeded to the throne; before Diocletians abdication some 35
legions were added to this number. How many new legions were formed during
the rule of Diocletian it can not be found out. Parallel to the number of legions,
the number of soldiers increased too. The numbers mentioned are not identical.
Some authors talk about 420,000 soldiers, while according to others Diocletian
expanded the Roman army up to 500 or 600 thousands of soldiers.
How many soldiers did the Roman Empire have to support during the time of
Diocletian? Lactantius estimated this to over a million but historians do not agree
with the statement. Jones reduced this number to 645,000 and MacMullen to
400,000.49 Besides the regular units, the number of soldies grew in the additional
units as well, so in the aforementioned times these consisted of about 150,000
soldiers.50 During the time of Diocletian, the Roman Empire probably doubled the
number of its legions and soldiers. However, this does not mean that the states
military power was doubled as well because, according to several sources, the
new recruiting way did not bring the best people into the army.
This growth in the number of soldiers strengthened the Empire but increased
the expenses of the state as well, so the former taxation system was unable to
provide enough income.
Balkans. The third type of recruits came from the liberated tribes from outside of
the Empire; those tribes were the allies of the Roman army. When they got money
and food in return, these allies agreed to help the Romans ght other enemies.
Considering the increased number of soldiers, which was due to Diocletian,
we should ask a question: Who could become a Roman soldier, more exactly, a
soldier of the Roman army; when and in what way?
Until Diocletians succession to the throne, the main way of forming the
army was by recruiting volunteers, mostly barbarians.53 These volunteers were
professionals who served in the army for a salary because that was probably
their only source of income. The army received poor people, peasants and
liberated slaves. After Diocletians reforms, a new way appeared what regards the
formation of the army. The state institutionalised the recruiting system, which
had always been relying on peasants. Arable lands were divided into units called
capitula and every unit had to provide for a certain number of recruits, who in
exchange would serve for indenite time. In case some of these units did not
have enough people to give the required number of recruits to the state, many of
them associated in order to provide the appropriate number of recruits.54
With this recruiting system the military quality decreased. That is, we can see
that recruits were not chosen as it had been done in republican times, but they
were sent by latifundium owners according to dened quota. We can assume
that those who were the least valuable had to serve army, while the obligation of
military service affected mostly the latifundium owners, who had to give a larger
number of recruits.
Such a recruiting system rather strengthened the authority of latifundium
owners by giving them more concessions besides many pretended and legal ones.
This would be one more element which contributed to the destabilisation of the
state, and it had serious consequences.
One of the developments was the introduction of the possibility of giving
money instead of recruits, this is the so called aurum tyronum. This obligation for
payment of a certain compensation instead of military service was a concession
practised just in some provinces.55 Later, this concession was given as a privilege
to certain classes of the Roman aristocracy, to senators, who had the possibility of
choosing between military service and compensatory payment.56
The logic of this payment (aurum tyronum) was that in case of not getting
recruits, the state could demand money in order to rent soldiers from among the
barbarians and the poor.
53 Zosimus 2, 15.
54 C. Th. 6, 13, 12; C. 12, 43, 13.
55 C. Th. 7, 13, 2; Lactantius 7, 5.
56 C. Th. 7, 13, 13.
Diocletians Military Reforms 139
57 Ntri 2011, 94 f.
58 C. Th. 6, 14.
140 Emilija Stankovi, Ph.D.
VII. Wages
The 3/4 of their wages, soldiers received in kind. Besides goods for their family,
the wages could include arms, horses and fodder. Sometimes these goods were
replaced by a certain amount of money. The amount of wages as well as the term
of the service depended on the position of the army.
Military service lasted for 20 years for comitatenses and 24 for the frontier
soldiers, but these latter were paid less than the comitatenses.
As it has already been mentioned, frontier soldiers had smaller wages probably
because of the land they were given, and they were treated as second class troops
who had easier task to do, and their service term was longer.
Besides their wages, soldiers, especially veterans had certain privileges such
as reduced taxes for their family, and they even got certain plots of land as gift.
Since the 3rd century, veteran soldiers had been given some land in the border
area, however with required frontier service.59
VIII. Estimate
From among the many changes introduced by Diocletian, the military reforms
were the most important. We can even say that some other changes were either
direct or indirect results of this one. Of course, the introduction of the taxation
system capitatioiugatio was a result of the need to increase income to face
growing expenses, from which the biggest one was the army. Even the Price
Edict, as in the introductory part Diocletian and his co-regent admitted, was a
result of concern for soldiers. The established measures of the military reforms
contributed to the stability of the state and mainly to the border protection of the
Empire by stopping barbarian attacks at least temporarily.
Good side of this reform was that the increased number of soldiers and the
better organisation of the army increased the states defence power. Besides the
larger number of soldiers, expenses were raised by the fast development and
by cavalry participation, which involved much higher expenses than what
was needed for the infantry. Was the state able to provide the necessary funds
compared to those already existent, and if it was, for how long and in what way?
The military reforms could not give any more permanent result.
Another bad result was the decline in quality of the military personnel.
The recruiting system did not bring the best people into the legions. Probably
latifundium owners gave their worse workers to the army.
59 C. Th. 7, 1.
Diocletians Military Reforms 141
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