It was the ancient Greeks who originally developed torsion siege engines, such as the onager and ballista, to smash through city walls and allow their troops to assault the breach. Although versions that used tension power had been in use for many years, torsion engines came into use around the beginning of the 4th century BC, and were probably invented by the Greek scientist Dionysius the Elder of Syracuse. However, these powerful weapons came to the fore and were used extensively during the Second Punic War, particularly for besieging large cities. During the conflict and following its defection to Hannibal's cause, the city of Syracuse was besieged by Rome, holding out for two years before falling. Although, ironically, Greek torsion technology aided the Romans in their successful completion of the siege, it was the mathematical genius of the inventor Archimedes that helped the Syracusan forces to hold out for as long as they did.
