Helepolis - Taker of Cities

Helepolis ( el. ἑλέπολις, English: "Taker of Cities") was an ancient siege engine invented by Polyidus of Thessaly and improved by Demetrius I of Macedon and Epimachus of Athens for the unsuccessful siege of Rhodes, based on an earlier, less massive design used against Salamis (305–304 BC). Descriptions of it were written by Dioeclides of Abdera, Vitruvius, Plutarch, and in the Athenaeus Mechanicus. If their numbers are accurate, it was the biggest and most powerful siege tower ever erected.

A large tapered tower, each side about 130 feet (41.1 m) high, and 65 feet (20.6 m) wide, it rested on eight wheels, each 12 feet (3.7 m) high. The three exposed sides were rendered fireproof with iron plates, and stories divided the interior, connected by two broad flights of stairs. The machine weighed 160 tons, and required 3,400 men working in relays to move it, 200 turning a large capstan driving the wheels via a belt, and the rest pushing from behind. Casters permitted lateral movement, so the entire apparatus could be steered towards the desired attack point, while always keeping the siege engines inside aimed at the walls, and the protective body of the machine directly between the city walls and the men pushing behind it.

The Helepolis bore a fearsome complement of heavy armaments, with two 180-pound catapults, and one 60-pounder (classified by the weight of the projectiles they threw) on the first floor, three 60-pounders on the second, and two 30-pounders on each of the next five floors. Apertures, shielded by mechanically adjustable shutters, lined with skins stuffed with wool and seaweed to render them fireproof, pierced the forward wall of the tower for firing the missile weapons. On each of the top two floors, soldiers could use two light dart throwers to easily clear the walls of defenders. As the Helepolis was pushed towards the city, the Rhodians managed to dislodge some of the metal plates, and Demetrius ordered it withdrawn from battle to protect it from being burned. Following the failure of the siege, the Helepolis was abandoned, and the people of Rhodes melted down its metal plating and used the materials to build a statue of their patron god, Helios, the Colossus of Rhodes, known as one of the ancient Seven Wonders of the World.

Vitruvius offers an alternative version, in which the Rhodians begged Diognetus, once the town architect of Rhodes, to find a way to capture the Helepolis. By cover of night he had the Rhodians knock a hole through the wall and channel large amounts of water, mud and sewage onto the area where the Helepolis was expected to attack the following day. Diognetus was successful; the tower was brought forth to the anticipated attack position and became irretrievably stuck in the mire. Once the siege was lifted, the Rhodians sold Demetrius' abandoned engines and used the money to erect the enormous Colossus of Rhodes.

Demetrius also attacked the city with a battering ram convert|180|ft|m long, operated by 1000 men, and he ordered the construction of "korax", huge drills for boring through walls. Due to his use of siege engines at Rhodes, Demetrius was given the name "Poliorcetes" (the Besieger). In subsequent ages, siege engineers continued to use the name "helepolis" for moving towers which carried battering rams, as well as machines for throwing spears and heavy stones.