Hannibal and the Punic Wars
Rome and Carthage — a wealthy Phoenician trading city near modern Tunis — fought three wars over 118 years for control of the western Mediterranean. In the second and most famous, the Carthaginian general Hannibal marched an army with war elephants from Spain over the Alps into Italy and destroyed Roman armies for fifteen years, annihilating perhaps 50,000 men in a single afternoon at Cannae. Rome lost battle after battle and simply refused to negotiate, eventually sending Scipio to attack Carthage itself, which forced Hannibal home to defeat at Zama in 202 BCE. Fifty years later Rome returned, razed Carthage, and sold its survivors into slavery. The wars turned an Italian republic into a Mediterranean empire — and gave it a taste for total victory that would, in time, unmake the republic itself.
A weapon or tactic upends the prevailing balance of power and renders an old defensive or offensive order obsolete.