Rams are probably as old as city walls. Basically a ram is a wooden pole or plank, usually tipped with a bronze or iron head. One surviving Greek example is dated to the C5 BC and is on display at Olympia; this photo comes from that museum.
Another ram, a purely wooden one, seems to have been recycled as the beam of a wine press, at the House of the Mysteries in Pompeii.
Throughout antiquity the real damage to city walls is done by the ram, not by catapults of any description. Huge structures are designed and built to shield and protect rams from defenders (see below). Early siege tactics and technologies are given in Thuc. 2.75-78 - very humorous in places. The first reference to a flame-thrower is at the battle of Delium (Athens-Thebes border), 424 BC, Thuc. 4.100; the second at Lekythus (Khalkidike) later in the same year but now by Brasidas rather than the Thebans, Thuc. 4.115. They were allies so technology transfer is possible; alternatively flame throwers might have been around for a while but we aren't told of them earlier than this.
The word catapult derives from the Greek katapeltês and perhaps means ‘against shield’; whatever the etymology, it was an antipersonnel weapon initially, and most catapults remained that; they were not often fired at walls with the intention of knocking the wall down; they were fired at the top of walls to keep the defenders heads' down while a ram attacked the wall below.
This is the first catapult. The weapon is named from fact that you need to push against it with your torso to load it. This is not a torsion catapult; the power comes from bent arms, just as in an ordinary bow. Invented c. 399 BC in Syrakuse. The whole city was making weapons, and some people were developing new ones; Diod. Sic. 14.41.
The first reference to and possibly use of artillery in the field (rather than around a city in a siege) is in 354: Onomarkhos the Phokian deployed them against Philip II, Polyainos 2.38.2. These are ‘stone-throwers’; perhaps the torsion-powered one-arm, better known by its Roman name the onager; perhaps a non-torsion design similar to that designed by Charon (dates unknown) as described in Biton (C3? BC) Construction of war engines and artillery 45-48.
Arkhidamos, son of Agesilaos, and king of Sparta 338-331, is said to have witnessed an early catapult brought from Sicily (Plutarch Sayings of Kings 191e). Non-torsion catapults are powered by a bow; they could have been given to Athens (by Dionysios I of Syrakuse) as early as 370. Sharp-casters (oxybeleis) are first mentioned in 340 (siege of Perinthus), stone-throwers in 334 (siege of Halikarnassos). Both may have been tension (bow) catapults. The earliest firm evidence for a torsion catapult is an Athenian inscription dated 330/29, talking of Eretrian machines in an Athenian store, so these machines were not then new. Between the two dates and places sits Philip II of Macedon; his chief engineer was one Poluidos of Thessaly. It is a natural deduction to associate him with the creation of torsion catapults, but it is still a deduction based on circumstantial evidence only. The Pergamon frieze representation (David Gill's photo of which is illustrated right) was made in the first half of the second century BC (between 197 and 159).
The standardized optimal dimensions and formulae for calibration seem to have been worked out between the 320s to 310s BC. Non-torsion catapults continue in production and use. The pictures below are of a model of Vitruvius' scorpion, built by Richard Cox, one of my students, which give a good idea of standard artillery in the C1.
All dimensions are based on the size of the spring hole, and it is determined by the size of missile one wishes to shoot (cf. caliber). The spring holes are the metal parts above and below the frame through which the sinew rope passes, over metal levers fixed to the top of the top spring hole and the bottom of the bottom spring hole. The sinew or human hair rope must be made carefully, and fitted very carefully, to ensure that both springs are equally tensed. If they are not, the missile will not fire straight and the frame will be unnecessarily stressed. We do not know how they made the rope: the ‘fullest’ evidence is Heron Belopoiika 81.10-11: ‘sinew rope which they plaited on a machine for twisting ropes’.
A mechanical scaling ladder, named after a type of musical instrument (BM reconstruction illustrated right) because it formed the same sort of shape. Reputedly invented by Herakleides of Tarentum. It is sometimes supposed that the original was created sometime after Diades; then Damis (and Ktesibios) designed the type that is described by Biton, and Herakleides then adapted that design for use from ships. The instrument looks like a ship version, which may support the view that that form is the original one (there are easier ways of getting men to the top of a wall if they are attacking from land rather than water).
The tortoise is a slow-moving (hence the name) cover, for a battering ram, or to provide cover for people digging holes, or filling trenches. Some had very sophisticated wheel structures allowing the tortoise to move in any direction.
Designed to be at least as high as the walls of the city they are brought against. Posidonios the Macedonian’s (another of Alexander’s engineers) tower is described in Biton 52-56. Other famous towers are those of Diades and Epimakhos (see Vitruvius bk 10). Heights given for latter vary between 86 and 100 cubits (= 40 – 46 metres; 130’ – 150’). By late antiquity many city walls were such that an elephant could serve as a natural siege tower (Prokopios Wars 8. 13. 4, 14. 35-6 and elsewhere).
Diades’ borer in Vitruvius 10.13.7 and Athenaios Mechanics 14 (now available in translation in Whitehead and Blyth, Athenaeus Mechanicus; also in Irby-Massie and Keyser 164). Note that there is much disagreement about how this machine worked. Diades' machine seems to work like a ram, whilst Apollodoros' was clearly something that rotated, something similar to a router, explicitly likened to a carpenter's tool, explicitly turned by a bow, apud [Heron of Byzantium] Par.Pol.17 (now available in translation in Sullivan, Siegecraft).
There is little evidence for the use of these before the C4 AD, but they are mentioned in passing by Philon c. 200 BC, and are more simple in design and construction than most other types of catapult. The photo shows the Ermine Street Guard's version, trigger just released and arm starting to move swiftly up towards the buffer.
Refs and further reading: T E Rihll The catapult: a history (2007), E W Marsden Greek and Roman Artillery, D. Whitehead and P.H. Blyth Athenaaeus Mechanicus, On Machines (2004), D.F. Sullivan Siegecraft: two tenth century instructional manuals by 'Heron of Byzantium' (2000)
