A fortified camp every night
When Roman legions were on campaign in hostile or uncertain territory, it normally did not simply stop and sleep wherever the day’s march ended. The soldiers built a fortified camp, often within a few hours, and then took it down and moved on the next morning. Ancient writers treated this habit as one of the army’s distinctive strengths. The Greek historian Polybius, writing in the second century BCE, gives a detailed description of the layout, and the Jewish historian Josephus later praised the speed and order of the process. A later Latin text on camp design, usually attributed to an author called Pseudo-Hyginus, adds further detail.
These descriptions idealise to some extent. Real camps varied with terrain, the size of the force and the period, though the broad pattern is recognisable.
How a camp was built
A marching camp was normally rectangular with rounded corners, a shape often compared to a playing card. Surveyors, who went ahead of the main column, chose the site and marked out the lines. The soldiers then dug a ditch and heaped the soil behind it to form a bank, or rampart. Each man carried an entrenching tool, and many also carried wooden stakes. The stakes were set along the top of the bank to form a palisade.
Inside, the plan was regular so that every unit knew where to pitch its tents without needing orders. The commander’s tent and the headquarters area were placed near the centre, with main streets crossing at right angles and gates in each side. Tents were assigned to a small group of soldiers who lived and messed together, traditionally eight men. Cavalry, baggage animals and supplies had their own areas, and open space was left between the tents and the rampart so that missiles thrown from outside would not easily reach the sleeping quarters.
Watches and passwords were set each night, and in the morning the camp was struck in a fixed order. In a dangerous area the camp might be dug carefully, whereas in friendly country the army might rest with lighter defences.
What remains today
Temporary camps leave faint traces: a low bank, a shallow ditch, a pattern of gateways. Because they were abandoned after a night or two, they rarely yield much dating evidence, and many are known only from aerial photographs and ground survey. Notable groups survive in northern Britain, where campaigns in Scotland left lines of camps along the invasion routes. Among better-preserved examples are the siege camps built around Masada in Judaea, where the Roman army besieged the fortress in the early 70s CE, with the camp walls still visible today.
Permanent forts and fortresses were a different matter. They were built to last, with timber and later stone buildings, and they often grew into towns. The marching camp was the field version of the same planning idea.
Feeding an army
An ancient army was a large moving community, and its food was a constant concern. The basic ration for a soldier was grain, typically wheat, which he ground into flour or baked into bread and sometimes cooked as porridge. This was supplemented with items such as bacon, cheese, vegetables and sour wine or vinegar mixed with water. Daily Roman food supplies in general followed what is covered under the Roman diet, though soldiers ate a simpler version.
Rations were issued through the army’s administration, and the cost was deducted from the soldier’s pay. Records from sites like Vindolanda in northern Britain, preserved on thin wooden writing tablets, mention grain, beer and other supplies, giving a rare glimpse of the paperwork behind the system.
A single legion included thousands of soldiers, and precise totals are uncertain, but the fodder for horses and mules could rival the human food bill.
Carrying and moving supplies
Soldiers carried a good deal of their own gear on the march, including personal equipment, tools and some food. The army also used pack animals and wagons, and sometimes civilian contractors, to move the heavier baggage. Where possible, armies moved supplies by water. Moving grain by boat along a river or by sea was far cheaper than hauling it overland, so many campaigns followed rivers and coasts, or began from a port. The state also stockpiled food in depots near the frontier. These depots connected to the road network, which let supplies reach distant garrisons, and travel along these routes is covered in the article on Roman road travel.
Armies also lived off the land. They requisitioned grain from local communities, took plunder, and demanded food as tribute from allies and conquered peoples. This was effective but could provoke hostility, and ancient commanders understood that harsh foraging could turn neighbours into enemies.
March discipline and pace
According to a late Roman author, Vegetius, the standard marching pace allowed an army to cover around twenty Roman miles in about five summer hours, with a faster pace sometimes used. Modern estimates vary, and the speeds depended on terrain, weather and the baggage train. The point is that training in marching was considered as important as training in weapons.
Health was part of logistics. Clean water and sensible camp siting reduced disease, a major killer in ancient campaigns, and the care of the wounded is covered in the story of Roman army surgeons.
Why it mattered
Logistics set the limits of what Roman commanders could attempt. An army that could not be fed could not stay in the field, however many battles it had won. Routine fortification meant that a surprise attack at night, one of the most dangerous moments for any army, rarely caught the Romans unprepared. Together, these habits help explain how Roman expansion was sustained across such large distances, even if they did not make every campaign a success.