Third Punic War
In the years between the Second and Third Punic Wars Rome was engaged in the conquest of the Hellenistic empires to the east and ruthlessly suppressed the Iberian people in the west, although they had been essential to the Roman success in the 2nd Punic War.
Romans still harbored a bitter hatred for Carthage, which had nearly destroyed them in the 2nd Punic War. Sentiments ran so strong that the great statesman Cato ended every speech, whatever the topic, with the phrase that has become the classic example of the passive periphrastic in Latin grammar: Delenda est Carthago. Carthage must be destroyed!
Meanwhile Carthage had regained much of its prosperity through trade, further alarming Rome that a revived Carthage could again threaten them with war. When the Carthaginians refused to accede to the Roman demand that they abandon their city and move inland into North Africa, the Roman Senate declared war on them and the city was immediately attacked, beginning the Third Punic War.
When, after a siege, Roman soldiers entered the city, they slaughtered all the inhabitants in a systematic house-to-house search. The world would never again experience such a butchering of non-combatants until World War II.
The city with its harbor was destroyed utterly, while the surrounding territory was sown with salt to make it unusable.