The Claw of Archimedes was an ancient weapon devised by Archimedes to defend the seaward portion of Syracuse’s city wall against amphibious assault. Although its exact nature is unclear, the accounts of ancient historians seem to describe it as a sort of crane equipped with a grappling hook that was able to lift attacking ships partly out of the water, then either cause the ship to capsize or suddenly drop it.
These machines featured prominently during the Second Punic War in 214 BC, when the Roman Republic attacked Syracuse with a fleet of at least 120 Quinqueremes under Marcus Claudius Marcellus. When the Roman fleet approached the city walls under cover of darkness, the machines were deployed, sinking many ships and throwing the attack into confusion. Historians such as Polybius and Livy attributed heavy Roman losses to these machines, together with catapults also devised by Archimedes.
The plausibility of this invention was tested in 1999 by the BBC in their Secrets of the Ancients and then again in early 2005 by the Discovery Channel in their television show Superweapons of the Ancient World by bringing together a group of engineers to try to conceive of, design and implement a design that was realistic given what we know about Archimedes. Within seven days they were able to test their creation. They did indeed succeed in tipping a model of a Roman ship over so that it would sink. While this does not prove the existence of the Claw, it does, at least, demonstrate its possibility.