Even the greatest imperial powers in history cannot expand forever, and are eventually
forced to come to terms with consolidation and defence in order to maintain their realm.
The Emperors of Rome adapted to this state of affairs by stationing their mighty legions
on the dangerous frontiers, and around the more important regions which they ruled - legions
which were often stationed in legionary fortresses. Welcome to our video on Imperial legionary
fortifications, how they were constructed and what life was like for the troops stationed
therein.
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Like so many other things in the Roman Empire, the concept of a legionary fortress came into
being during the reign of Emperor Augustus - the founder of Rome’s imperial period.
Before this much-needed era of reformation after the turmoil of the Late Republic, legions
had traditionally been raised for specific military ventures, and were then disbanded
after this purpose was complete. Provinces such as Spain always required a resident army
wintering there, due to the fact that the far-off Roman territories were too far from
the heartland to constantly shift men back and forth. This was also the case with expansive
and lengthy military campaigns such as Caesar’s conquest of Gaul, which necessitated the quartering
of legions within the occupied lands. However, it is only from the time of Augustus
onwards that we discover standing armies billetted in permanent quarters in the Empire’s various
far-flung provinces, from Northern Britain to the distant reaches of Egypt. The first
true fortress isn’t known, but we do know that during the expeditions across the Rhine
into Germany during the final years of the first century BC, fortresses were constructed
in enemy territory in order to hold parts of this wild landscape. This didn’t last
long however, and the subsequent disaster at the Teutoburg Forest led to the Roman military
abandoning these fortresses across the Rhine. Whatever the case, we can speculate that Roman
military leaders took these ‘prototype’ fortresses and merged them with legionary
practices from centuries gone by, in order to implement the new defences.
Each legion was probably responsible for the construction of its own home fortress, and
could call upon a number of specialists from its own ranks. This probably included architects,
engineers, surveyors, plumbers, roofers, carpenters, stonemasons and so on. As well as providing
skilled experts, the legion in question would also provide the raw manpower necessary for
clearing the chosen building site of unwanted detritus, and for actually building the fortress.
All of this makeshift construction force would be supervised by the legion’s praefectus
castrorum - the ‘prefect of the camp’ - who was an experienced officer promoted
after extensive service as a centurion. While this process led to a relatively standardised
fortification design, and it is clear that there was at least a basic blueprint, no two
were totally identical. Most fortresses, for example, were based on a rectangular perimeter
of 20 to 25 hectares. However, there were outliers: for example, two German legions
during the late 1st century AD differed in that one of them was based in an abnormally
small fortress of 16.5 hectares at Nijmegen, while the other legion had an abnormally large
27 hectare fort at Bonn. Every fortress had four gateways, one for
each of its four sides. The front gate - also known as the porta praetoria - and the rear
gate - known as the porta decumana - were both half way along the rectangle’s short
sides. The longer sides of the fortress were different, with each of the gates on these
edges - known as the portae principales - being constructed a third of the way down the length.
These side gates were known by this name because they were both connected by the same laterally
running road within the fortress itself, which passed in front of the principia, the function
of which we shall discuss in detail a bit later. For now it’s enough to say that the
principia was centrally placed, interrupting the main road running lengthways and splitting
it into two sections. The part running from the front gate to the
principia was known as the via praetoria and terminated at the via principales, while the
rear length - the via decumana - began with the via quintana - a road running behind the
principia. These weren’t the traditional Roman roads that we know on the Italian Peninsula,
and were typically 7 to 8 metres wide, constructed with gravel over a bed of cobbles. It was
tilted slightly outwards with stone-built side drains, so that any accumulating water
would flow off and into the drain, rather than pooling on the road itself. Normally,
the road builders would also add a sewer underneath in order to more effectively carry waste away
from the fortress, making disease less likely among the troops. The final road ran around
the internal perimeter of the fortress behind its defences, called the via sagularis, and
was constructed to facilitate the speedy mustering of troops.
The criss-crossing road system essentially divided the fortress into five zones: two
zones at the front and back known as the praetentura and the retentura respectively, each of which
comprised a left and right zone bisected by the structure’s roads. This left a singular
remaining zone sandwiched between the via principalis and the via quintana, known as
the latera praetorii, or ‘flanks of the praetorium’, known as such because the buildings
here were arranged around the praetorium - the commander’s residence.
The Roman tendency to standardise even extended to the size of each area, as we can see from
archaeological digs performed on roman fortresses across Europe. In most fortresses, the central
zone was two blocks, or as the Romans called them, scamna, deep, with one fronting onto
the via principalis, while the second faced the other way, onto the via quintana. The
retentura was only one block deep in order to accommodate the lodgings of four cohorts,
two on either side of the via decumana, which the praetentura was two or three deep.
Now we’ll discuss some of the key buildings and features of each Roman fortress, examining
how they impacted the lives of everyday soldiers and their commanders alike. We will start
with the legion’s headquarters - the aforementioned principia. This command building occupied
a central position in each legionary base, and was modelled after the famous Roman forum
which existed in most towns of the Imperial period. A principia was entered through a
monumental gate like structure known as a groma, due to the fact that it was also the
position of the reference point for a legion’s surveyors.
Inside the gate was an open, colonnaded courtyard surrounded by yet another drain, which collected
rainwater from the thatched rooftops around it much like those on the roads. Moreover,
the runoff water was often fed into a storage system, such as the one at Inchtuthil in Scotland
which had a capacity of somewhere around 47,500 litres. On three sides of the courtyard were
rows of rooms, long thought to have served as armouries and other storage chambers, while
the fourth side was occupied by a long hall, known as a basilica. This was a place of assembly
for the troops, with a tribunal at one end (and sometimes even at both ends). Its name
would come to denote types of church in later eras. Behind the basilica was a series of
offices which flanked the central legionary shrine, where the revered aquila was kept
- the eagle standard - in addition to 59 centurial standards - signa.
It’s clear that this building was an administrative and financial centre for the legion, and we
can see this in multiple examples we have found inside excavated principia. Standard-bearers
of the Roman army often had financial responsibilities, so in many of the fortresses the floor of
its central shrine was elevated in order to create a strong-room in the basement. Here,
the legion’s official funds were kept, in addition to the savings of individual soldiers.
It was essentially an ancient safe vault. Various clerks and other administrators necessary
to keep the legionary cogs turning probably occupied the other offices, processing various
documents, organising logistics and other routine tasks.
One room at Lambaesis in modern Algeria contained an inscription confirming the excavated room
as a tabularium legionis - or ‘records office of the legion’. On the inscription was a
list of staff, including an ‘adjutant’, a ‘registrar’ and several lower secretaries.
In addition to its mundane bureaucratic function, it’s clear that this building also had religious
overtones, which is shown by the frequent excavations of altars at the old sites of
these fortresses. All evidence brings us to the conclusion that the principia was therefore
the main hub of the legion - its religious centre and its administrative nexus - where
its official records were kept and where its funds were disbursed. Moreover, it was often
the actual physical centre of the entire legion, where a commanding officer could assemble
the troops for an address. Said commander had levels of accomodation
which were very different from the massed barrack blocks of the soldiers. This was known
as the praetorium, located behind or beside the principia. As this was normally the dwelling
of a lofty senator of the Roman aristocracy, or a commander appointed directly by the emperor,
the praetorium followed the plan of a high-class mediterranean villa, bringing all of the luxuries
to which such highborn figures were accustomed to the provinces, which were often far from
Rome itself. Because of this, historians often refer to this building colloquially as the
‘legate’s palace’. Aside from living rooms and gardens for use
by the commander’s family, a praetorium had to possess servants’ quarters and public
rooms, the latter of which served as an area where a senatorial commander might convene
with his officers and entertain distinguished visitors. Perhaps a legate might enhance his
relationship with a pro-Roman Celtic chieftain in Britannia by inviting the man to dine and
bathe in his home, for example, before discussing business in the Roman manner. Slightly less
luxurious but still of a relatively high class were the domus - or ‘tribune’s houses’
- grouped in an area along the via principalis, and having a dining room, colonnaded courtyard,
and other standard Roman mediterranean designs. Because every fortress was in effect a self-contained
military town containing as many as 6,000 troops, the greater part of its area was taken
up by accomodation for the legionaries and their officers. Despite this, however, many
other buildings were usually included for utility. Large courtyard structures meant
for industrial production have been found at such sites as Exeter and Inchtuthil and,
at the latter, excavator Sir Ian Richmond found a hoard of a million nails and nine
iron tyres, buried when the fort was abandoned. A similarly sized courtyard in the retentura
at Caerleon may have also been one of these industrial workshops, also known as fabrica,
as it was associated with lead-working waste material.
Activities in these facilities were practiced as a side profession by ordinary legionaries
with an expertise in specific skills or crafts, legionaries who were known as immunes. As
skilled workers, these soldiers were often exempt from the back-breaking labour undertaken
by their unskilled comrades, such as digging ditches and patrolling the ramparts.
Many of these technical crafts were linked to the manufacturing or repair of equipment,
and were therefore key in enhancing the operations of a legion as a whole. One papyrus from Egypt
confirms the assumption that such activity must have taken place in large workshops,
when it refers to work ‘in fabrican legionis’, or ‘in the legionary workshop’. Archaeologists
have discovered three main varieties of fabricae - a long, rectangular hall, the double hook
or U-shaped building, and the ‘bazaar’ type complex of maze-like interconnected rooms.
It is common to find evidence of smithies within legionary fortresses, but they must
have had workshops for leatherworking, woodworking, glassmaking and other trades.
Also universal within the legion’s own town was the hospital, or ‘valetudinarium’,
a building which Hyginus recommends should be located as far as possible away from the
workshops, in order to make sure that recovering patients get the peace and quiet they need.
However, there was no standard position for a legionary hospital. For example, the buildings
at Caerleon, Vetera, Novae and Lauriacum were in the praetentura, while a site in the latera
praetorii was selected at Inchtuthil, Neuss, Carnuntum and Bonn.
The building itself always followed the same plan: two rows of rooms, separated by a corridor,
ran around the four sides of an open, colonnaded courtyard. Most of the rooms were arranged
in pairs of wards flanking a small vestibule, giving access to the corridor. The vestibule
gave the wards a degree of privacy from the outside world, while the corridor permitted
staff to circulate as needed around the hospital. Even evidence of underfloor heating, known
as a hypocaust, was found at Caerleon, while the hospital at Vetera had small baths and
a latrine. Dedications to the health deities Hygeia and Telesphoros were made at shrines
in most hospitals, and it has been speculated that the entire hospital was a religious monument
of sorts. In a truly Roman fashion, each fortress was
provided with a typical hallmark of Roman civilisation at that time in history: the
thermae, or bathing complex, for use of the troops. These were built from masonry most
of the time, even in the ‘turf and timber’ fortress of the early period, almost certainly
to reduce the risk of fire spreading from this building’s massive furnaces, which
were used to heat the water. Using stone would also prevent deterioration from dampness and
maintain a constant temperature in the various rooms.
Interestingly, while the thermae did not have any designated position in each fortress,
they were often placed near the hospital, a fact which emphasizes the connection between
health and cleanliness even in the classical world. As the largest structure in each fortress,
the baths also represented a true feat of Roman engineering, and would probably have
been considered a wondrous miracle by many of the less technologically advanced ‘barbarian’
peoples to whom they were first introduced, such as the Britons.
At Caerleon, the vaulted ceiling of its thermae stood a proud 15 meters above the floor, and
the entire bathing complex covered a huge hectare in space. In Roman culture, bathing
was not only a matter of getting clean, but also had a recreational and social function,
which we will probably discuss in a future video. The excavator at Caerleon, George Boon,
noted an inscription which concisely shows us a legionary’s philosophy when it comes
to his free time: ‘To hunt, to bathe, to gamble, to laugh, this is living!”
In warmer climates such as North Africa and Egypt, outdoor swimming pools and exercise
yards were constructed, while in chillier climates such as Gaul or Britannia, indoor
exercise halls and swimming pools were necessary, in Chester, for example. The layout of the
thermae itself were as follows: a changing room, followed by three main halls laid out
in sequence, beginning with the frigidarium - or ‘cold room’. It was unheated and
usually comprised one or more cold water wash basins and plunge pools. A thermae’s second
room was the tepidarium - or ‘warm room’ - which was moderately heated, while the third
was a caldarium, or hot-room, which had a hot water pool. A bather would progress through
the pools at increasing temperatures in order to induce a cleansing level of perspiration,
at which point dirt and grime could be scraped from the oiled body with a bronze tool known
as a strigil.
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