Readiness and disposition The military capability of Rome – its preparedness or readiness – was always primarily based upon the maintenance of an active fighting force acting either at or beyond its military frontiers, something that historian Luttwak refers to as a "thin linear perimeter. This is best illustrated by showing the dispositions of the
Roman legions, the backbone of the Roman army. Because of these deployments, the Roman military kept a central
strategic reserve after the
Social War. Such reserves were only re-established during the late empire when the army was split into a border defense force and mobile response field units.
Power projection The Roman military was keen on the doctrine of
power projection – it frequently removed foreign rulers by force or intimidation and replaced them with puppets. This was facilitated by the maintenance, for at least part of its history, of a series of
client states and other subjugated and buffer entities beyond its official borders, although over which Rome extended massive political influence and military threat to keep them loyal. However, this could also lead to the payment of immense subsidies to foreign powers to keep a frontier quiet.
Logistics The empire's system of building an extensive and well-maintained road network, as well as its absolute command of the Mediterranean for much of its history, enabled a primitive form of
rapid reaction, also stressed in modern military doctrine. During the imperial period, some border regions had
limites built, forts that would sustain a Roman presence, deal with small incursions themselves, and slow down larger incursion to enable aid to be sent. The Roman military had an extensive logistical supply chain. There was no specialised branch of the military devoted to logistics and transportation, although this was to a great extent carried out by the
Roman navy due to the ease and low costs of transporting goods via sea and river compared to overland. Work managing supplies and logistics was probably part of the standard career path of Roman elites, something acquired while working as
military tribunes managing foraging expeditions, and reinforced in later positions. There is archaeological evidence that Roman armies campaigning in
Germania were supplied by a logistical supply chain beginning in Italy and
Gaul, then transported by sea to the northern coast of Germania, and finally penetrating Germania via barges on inland waterways. Forces were routinely supplied via fixed supply chains. Roman armies in enemy territory obtained their food many ways simultaneously; they would forage for food, purchase food locally, raid local foodstores, and have food shipped to them by supply lines.
Peter Heather writes that a single legion would have required 13.5 tonnes of food per month, and attempting to get all that food in just a single way would have proved impossible.
Policing For the most part, Roman cities had a civil guard used for maintaining peace. Due to fear of rebellions and other uprisings, they were forbidden to be armed at militia levels. Policing was split between the city guard for low-level affairs and the Roman legions and auxiliary for suppressing higher-level rioting and rebellion. This civil guard created a limited strategic reserve, one that fared poorly in actual warfare.
Engineering , designed by the Roman army to breach the fortress' walls The military engineering of
Ancient Rome's armed forces was of a scale and frequency far beyond that of any of its contemporaries. Indeed, military engineering was in many ways institutionally endemic in Roman military culture, as demonstrated by the fact that each Roman
legionary had as part of his equipment a shovel, alongside his
gladius (sword) and
pila (spears). Heather writes that "Learning to build, and build quickly, was a standard element of training". This engineering prowess was, however, only evident during the peak of Roman military prowess from the mid-republic to the mid-empire. Before the mid-republic period, there is little evidence of protracted or exceptional military engineering, and in the late empire likewise, there is little sign of the kind of engineering feats that were regularly carried out in the earlier empire. Roman military engineering took both routine and extraordinary forms, the former a proactive part of standard military procedure, and the latter of an extraordinary or reactionary nature. Proactive military engineering took the form of the regular construction of fortified camps, in road-building, and the construction of
siege engines. The knowledge and experience learned through such routine engineering lent itself readily to any extraordinary engineering projects required by the army, such as the
circumvallations constructed at
Alesia and the earthen ramp constructed at
Masada. This engineering expertise practiced in daily routines also served in the construction of siege equipment such as
ballistae,
onagers and
siege towers, as well as allowing the troops to construct roads, bridges, and fortified camps. All of these led to strategic capabilities, allowing Roman troops to, respectively, assault besieged settlements, move more rapidly to wherever they were needed, cross rivers to reduce march times and surprise enemies, and to camp in relative security even in enemy territory. ==International stance==