In ancient Rome, various siege and field machines had a very important position during the fighting. Thanks to them it was possible to conquer fortifications, even the best-situated ones, and to hit the enemy long distance with missiles. There were also wolf holes in everyday use. During the conquests, Rome built and modernized the machines in such a way that they had amazing properties. Without their help, the Romans would certainly not have achieved such a big advantage over their opponent.
The approach of the ancient Romans to siege engines was different than in other civilizations. Roman engineering-focused entirely on functionality, often at the expense of size. The Greek architect and constructor Epimachus of Athens designed the siege tower, which was used during the siege of Rhodes in 304 BCE. It had a base area of 21 sq m and a height of 40 meters and was mainly intended to intimidate the defenders. For example, the Romans built towers 15 and 22 meters high during the siege of Jotapata (during the Jewish war) in 67 CE. The effectiveness of the combat machines was crucial. This, in turn, led to the problem of machine building and increasing aggressiveness on the battlefields.
One of the most momentous innovations was the dissemination and inclusion in the legion of various types of neurobalistic propellants. Due to the constructions, the propelling machines are divided into:
- neurobalistic in which throwing a bullet was possible due to the expansion of a flexible material, e.g. a rope in which energy was accumulated by bending or twisting it;
- barobalistic, in which energy is accumulated in the weight of the load, which was to be shot, raised to a certain height. Missile throwing was possible thanks to the lever having two uneven arms.
Due to the trajectory of the projectile, these machines are divided into: I. propelling projectiles; II. throwing projectiles steeply.
They were used mainly during the initial stages of fighting, during a siege or during defence activities. These were: ballistics firing flat-track missiles and catapults that fired projectiles in a stromotor manner. The latter include onagra (probably invented in Greece in 385 BCE) and scorpions.
The most effective type of artillery during open-air battles was the field version of onagers. During the march, they were transported on rolling stock carts (in whole or in parts). Constant service consisted of 8 artillery gunners (called ballistiaria or doctores ballistarum), although only 2 operators were needed to shoot themselves; according to A. Michałek, the average frequency of firing shells without aiming regulation was 1 shot for 5 minutes.
In the days of Julius Caesar, each legion had approx. 55 ballists, throwing special projectiles weighing up to 30 kg, which were launched at a distance of 350 m. They were 10 more catapults and onagers and a number of scorpions. The former ejected heavy missiles weighing up to 80 kg. They had the form of stone or lead balls and powerful beams. Onagers usually threw 50 kg bullets at a distance of up to 450 m. Smaller ammunition in the form of stones, which were wrapped in material, was also used as an effective means of destruction of the enemy. Incendiary missiles were also used to create panic in the ranks of the besieged enemy. They were usually caned shots. They were connected to the tip with iron sheet cut in many places. Before firing, the combustible material accumulated in their hollow centre was set on fire. To get the expected effect, you should avoid sudden movements when firing an arrow. Ammian mentions that slow-fired arrows burn for so long that they can be extinguished only by covering with sand. In addition, containers with kerosene, hot tar or charcoal, and even baskets filled with venomous snakes, were used as ammunition. Scorpions usually shot bolts with pointed tips. At an inclination of 45 degrees, they hit the target at a distance of 185 meters.
In the 1st century BCE, the Romans perfected the technique of capturing coastal towns. The use of siege machines called “samba” was widespread (for the first time this type of machine was used during the siege of Syracuse in 213 BCE), which was placed directly on two connected five-rowers, thus forming a siege ship. Here is how Polibiusz describes them:
Meanwhile Marcellus was attacking the quarter of Arcradina from the sea with sixty quinqueremes, each vessel being filled with archers, slingers and javelin-throwers, whose task was to drive the defenders from the battlements. Besides these vessels he had eight quinqueremes grouped in pairs. Each pair had had half of their oars removed, the starboard bank for the one and the port for the other, and on these sides the vessels were lashed together. They were then rowed by the remaining oars of their outer sides, and brought up to the walls the siege engines known as sambucae. These are constructed as follows. A ladder is made, four feet in width and high enough to reach the top of the wall from the place where its feet are to rest. Each side is fenced in with a high protective breastwork, and the machine is also shielded by a wicker covering high overhead. It is then laid flat over the two sides of the ships where are lashed together, the top protruding a considerable distance beyond the bows. To the tops of the ships’ masts are fixed pulleys with ropes, and when the sambuca is about to be used, the ropes are attached to the top of the ladder, and men standing in the stern haul up the machine by means of the pulleys, while others stand in the bows to support it with long poles and make sure that it is safely raised. After this the oarsmen on the two outer sides of the ships row the vessels close inshore, and the crews then attempt to prop the sambuca against the wall. At the top of the ladder there is a wooden platform which is protected on three sides by wicker screens; four men are stationed on this to engage the defenders, who in the meanwhile are struggling to prevent the sambuca from being lodged against the battlements. As soon as the attackers have got it into position, and are thus standing on a higher level that the wall, they pull down the wicker screens on each side of the platform and rush out on to the battlements or towers. Their comrades climb up the sambuca after them, the ladder being held firm by ropes which are attached to both ships. This device is aptly named, because when it is raised the combination of the ship and the ladder looks remarkably like the musical instrument in question.
– Polybius, Histories, VIII, 6
An important contribution to Julius Caesar’s , in connection with the widespread dissemination of propellant machines, was the development of uniform principles of siege art. According to the Dupuy brothers, in order to make an effective siege it was necessary to:
- Identify the area where enemy fortifications are located to protect wood, stone, food, and draft animals.
- Set up a fortified camp in the area.
- Begin the construction of movable shielding shields, thanks to which you could get to the most advanced trenches and siege divisions.
- Build redoubts along the fortification lines and connect them with contravalation lines.
- Cover the circumvalve shafts.
- Build protective passages towards the enemy walls line.
- Build a mound on which siege towers were usually built. They were usually moved on thick round logs. Their front wall was covered with soaked animal skins for protection against incendiary projectiles.
- Cover the moat surrounding the fortifications on the sections where the attack is planned.
- Join the general assault.
There are two main types of assault on enemy fortifications:
- About weak walls: They were usually obtained by quickly approaching the walls and throwing stones at the defenders with a hail of stones and incendiary projectiles. When they were forced to retreat from the walls, they climbed the ladders.
- About strong walls: They were obtained by siege using propelling machines. In order to get past the walls, general assaults were carried out using hooks to tear stones out of the walls and drills. In the meantime, they protected themselves, forming a turtle formation (testudo) of 27 legionaries. In addition, rams turned out to be very useful when besieging various types of fortifications (According to Vitruvius, Carthaginians used it for the first time during the siege of Gades).
To protect the legionaries approaching the enemy walls, special covers were used in the form of roofs and walls: “raccoons” (vineae) and so-called “turtles” (plutei). Generally speaking, the plutei shield protected legionaries from frontal fire, and vineae shielded soldiers transporting soil/sand in buckets. These constructions were covered with fresh animal skins, often stuffed with seagrass or straw soaked in vinegar. The purpose of this action was to prevent any fires.
The Romans also naturally used rams and wooden constructions. They had long and thick beams finished with an iron element. The beam was hung on iron bars arranged transversely. A group of soldiers pulled her back and then pushed her forward to break down the gate or walls. Another type of ram had a beam placed on the ropes, where, using the tension of the ropes, they hit the gate.
Various types of wood were used for the construction of machines and structures depending on the needs. The most ordinary layers of boards were used to cover the siege towers, when oak or ash were used in the construction of foundations: wheels or chassis. To prevent wood burning, the layers of clay or cast iron plates were used (apart from the abovementioned means). The latter method was very risky for siege towers, as they could collapse under the weight of metal. Animal skin was the most effective, as clay could always be washed off.
During the assault, the Romans also used many other technical innovations, not always native ones. Vitruvius devotes a lot of space in his work to inventions of Diades of Pella (designer from the 4th century BCE), writing:
[…] he was the inventor of ambulatory towers, which he caused to be carried from one place to another by the army, in pieces, as also of the auger and the scaling machine, by which one may step on to a wall; as also the grappling hook, which some call the crane (grus).
– Vitruvius, De architectura, X, 13, 3-4.
In favourable weather conditions, it was possible to carry out the excavation. The architect Trypho of Alexandria came up with an effective idea of preventing hostile excavations:
Trypho, of Alexandria, who was the architect to the city, made several excavations within the wall, and, digging through, advanced an arrow’s flight beyond the walls. In these excavations he suspended brazen vessels. In one of them, near the place where the enemy was forming his mine, the brazen vessels began to ring, from the blows of the mining tools which were working. From this he found the direction in which they were endeavouring to penetrate, and then prepared vessels of boiling water and pitch, human dung, and heated sand, for the purpose of pouring on their heads. In the night he bored a great many holes, through which he suddenly poured the mixture, and destroyed those of the enemy that were engaged in this operation.
– Vitruvius, De architectura, X, 16, 10
The excavation was under the cover of the siege shed. Polybius describes this kind of way of breaking into enemy fortifications:
[Romans] took to mining and digging underground. Having secured the middle one of the three machines they previously had on this site and covered it carefully with wattle screens, they constructed in front of it a covered gallery running parallel to the wall for about a hundred yards, from which they dug continuously by day and night, employing relays. For a good many days they carried out the earth by the underground passage without being noticed by the defenders, but when the heap of earth became considerable and visible to those in the city, the leaders of the besieged set vigorously to work to dig a trench inside the wall parallel to the wall itself and to the gallery in front of the towers. When it was sufficiently deep, they lined the side of the trench next the wall with exceedingly thin plates of brass, and advancing along the trench with their ears close to these, listened for the noise made the miners outside. When they had noted the spot indicated by the reverberation of some of the brass plates, they began to dig from within another underground passage at right angles to the trench and passing under the wall, their object being to encounter the enemy. This they soon succeeded in doing, as the Roman miners had not only reached the wall but had underpinned a considerable part of it on both sides of their gallery of approach.
– Polybius, Histories, XXI, 28, 5-10
The activities described above were carried out with simultaneous firing of machines and archers from several-story siege towers, whose height was 10-20 meters. If the tower reached the top of the walls, a bridge was thrown, after which soldiers reached the walls.