The Third Punic War (149–146 BC) was the third and last of the Punic Wars fought between Carthage and Rome. The war was fought entirely within Carthaginian territory, in what is now northern Tunisia. When the Second Punic War ended in 201 BC one of the terms of the peace treaty prohibited Carthage from waging war without Rome's permission. Rome's ally, King Masinissa of Numidia, exploited this to repeatedly raid and seize Carthaginian territory with impunity. In 149 BC Carthage sent an army, under Hasdrubal, against Masinissa, the treaty notwithstanding. The campaign ended in disaster as the Battle of Oroscopa ended with a Carthaginian defeat and the surrender of the Carthaginian army. Anti-Carthaginian factions in Rome used the illicit military action as a pretext to prepare a punitive expedition.

Later in 149 BC a large Roman army landed at Utica in North Africa. The Carthaginians hoped to appease the Romans, but despite the Carthaginians surrendering all of their weapons, the Romans pressed on to besiege the city of Carthage. The Roman campaign suffered repeated setbacks through 149 BC, only alleviated by Scipio Aemilianus, a middle-ranking officer, distinguishing himself several times. A new Roman commander took over in 148 BC and fared equally badly. At the annual election of Roman magistrates in the spring of 147 BC the public support for Scipio was so great that the usual age restrictions were lifted to allow him to be appointed consul and commander in Africa.

Scipio's term commenced with two Carthaginian successes, but he tightened the siege and started to build a large mole to prevent supplies from getting into Carthage via blockade runners. The Carthaginians had partially rebuilt their fleet, and it sortied, to the Romans' surprise. After an indecisive engagement, the Carthaginians mismanaged their withdrawal and lost many ships. The Romans then built a large brick structure in the harbour area that dominated the city wall. Once this was complete, Scipio led a strong force that stormed the camp of Carthage's field army and forced most of the towns and cities still supporting Carthage to surrender. In early 146 BC the Romans launched their final assault and, over six days, systematically destroyed the city and killed its inhabitants; only on the last day did they take prisoners, 50,000 of them, who were sold into slavery. The conquered Carthaginian territories became the Roman province of Africa, with Utica as its capital. It was a century before the site of Carthage was rebuilt as a Roman city.

The main source for most aspects of the Punic Wars is the historian Polybius (c. 200 – c. 118 BC), a Greek sent to Rome in 167 BC as a hostage. His works include a now-lost manual on military tactics, but he is best known for The Histories, written sometime after 146 BC. He accompanied his patron and friend, the Roman general Scipio Aemilianus, in North Africa during the Third Punic War; this causes the normally reliable Polybius to recount Scipio's actions in a favourable light. In addition, significant portions of The Histories' account of the Third Punic War have been lost.

The account of the Roman annalist Livy, who relied heavily on Polybius, is much used by modern historians of the Punic Wars, but all that survives of his account of events after 167 BC is a list of contents. Other ancient accounts of the Third Punic War or its participants which have also been largely lost include those of Plutarch, Dio Cassius and the Greek Diodorus Siculus. Modern historians also use the account of the 2nd-century AD Greek Appian. The modern historian Bernard Mineo states that it "is the only complete and continuous account of this war". It is thought to have been largely based on Polybius's account, but several problems with it have been identified. These issues mean that of the three Punic Wars, the third is the one about which the least is reliably known. Other sources include coins, inscriptions, archaeological evidence and empirical evidence from reconstructions.

In the mid-2nd century BC Rome was the dominant power in the Mediterranean region, while Carthage was a large city-state in the north east of what is now Tunisia. Carthage and Rome had fought the 23-year-long First Punic War from 264 to 241 BC and the 17-year-long Second Punic War between 218 and 201 BC. Both wars ended with Roman victories; the Second when the Roman general Scipio Africanus defeated Hannibal, the premier Carthaginian general of the war, at the Battle of Zama, 160 kilometres (100 mi) south-west of Carthage. Africanus imposed a peace treaty on the Carthaginians which stripped them of their overseas territories and some of their African ones. An indemnity of 10,000 silver talents was to be paid over 50 years. Hostages were taken and Carthage was prohibited from waging war outside Africa—and could wage war in Africa only with Rome's express permission. Many senior Carthaginians wanted to reject the treaty, but Hannibal spoke strongly in its favour and it was accepted in spring 201 BC. Henceforth, it was clear that Carthage was politically subordinate to Rome.

At the end of the war Masinissa, an ally of Rome, emerged as by far the most powerful ruler among the Numidians, the indigenous population which controlled much of what is now Algeria and Tunisia. Over the following 50 years, he repeatedly took advantage of Carthage's inability to protect its possessions. Whenever Carthage petitioned Rome for redress or permission to take military action, Rome backed Masinissa and refused. Masinissa's seizures of and raids into Carthaginian territory became increasingly flagrant. In 151 BC Carthage raised a large army commanded by the previously unrecorded general Hasdrubal and, the treaty notwithstanding, counter-attacked the Numidians. The campaign ended in disaster at the Battle of Oroscopa and the army surrendered. Many Carthaginians were subsequently massacred by the Numidians. Hasdrubal escaped to Carthage, where, in an attempt to placate Rome, he was condemned to death.

Carthage paid off its indemnity in 151 BC and was prospering economically but was no military threat to Rome. Nevertheless, there had long been a faction within the Roman Senate that had wished to take further military action against Carthage. For example, the dislike of Carthage by the senior senator Cato was so well known that since the 18th century (AD), he has been credited with ending all of his speeches with Carthago delenda est ("Carthage must be destroyed"). The opposing faction included Scipio Nasica, who argued that fear of a strong enemy such as Carthage would keep the common people in check and avoid social division. Cato was a member of an embassy to Carthage, probably in 153 BC, and noted her growing economy and strength; Nasica was likely a member of the same embassy. Using the illicit Carthaginian military action as a pretext, Rome began preparing a punitive expedition.