The Second Puno-Roman War had raged for two years, and Rome became desperate after a string of catastrophic defeats at the hand of Hannibal, son of Hamilcar Barca. Hamilcar had served as the great Carthaginian commander in the First Punic War and went into exile in Iberia after angrily killing Hanno II, leader of the peace-mongers of Carthage, who had demobilized the Carthaginian navy and allowed the Romans to rebuild their own fleet. Hamilcar had passed on his distrust and hatred of the Romans to Hannibal, who set off across Gaul in a surprise attack across the Alps that caught the Romans with their sandals untied. The Gauls of northern Italy rose up around him, and Hannibal began a years-long campaign around the Italian peninsula that would end with the defeat of Rome.
The Romans were determined to have another, final battle with the largest army anyone had attempted on the peninsula. Working under both consuls, they formed up a force of nearly 90,000 men, which included quaestors, tribunes, and even senators from the 300. The enormous army attacked Hannibal, who feinted a retreat, catching the much larger army in an enveloping maneuver that allowed the Carthaginians to surrounded and again slaughter Romans by the tens of thousands. After the battle, some 50,000 Romans lay dead, including much of the governors of Rome itself. According to legend, every single Roman was related directly to someone killed in battle. Hannibal's army, meanwhile, had only lost some 8,000.
At the victory, Hannibal's Nubian commander of cavalry, Mahrabal, approached him, saying that he would ride ahead of the main army and begin the attack on Rome. Hannibal, however, was slow to agree. His was a field army, and they did not have the siege weapons necessary to take Rome. Moreover, the Romans still had many allies as well as a seemingly unbreakable resolve, and moving on the city would potentially cut off his supply lines. Finally, Hannibal's men had fought long and hard, and he sought to reward them with three days of looting the corpses from the field. Mahrabal responded, “Truly the Gods have not bestowed all things upon the same person. Thou knowest indeed, Hannibal, how to conquer, but thou knowest not how to make use of your victory.”
Hannibal,suffering a migraine from his strained vision after having lost an eye before the Battle of Lake Trasimene, responded that Mahrabal could do as he saw fit, and the Nubian took an army of volunteers to begin the siege of Rome with Hannibal's forces to follow after their days of rest. He sent a case of some 200 rings cut from the fingers of dead Roman nobles to the Carthaginian senate, asking for reinforcements and equipment necessary to finish the war. After much debate, Carthage agreed, and they gained new allies as Grecian Sicily revolted against Rome and Macedon joined Hannibal's cause.
Even with an upgraded army that summer, the siege of Rome was not easy. Rather than a uniform siege line, Hannibal stretched his resources and emulated Mahrabal's tactics of constant patrols on horseback with skirmishers defeating any supply trains attempting to sneak into Rome. The Romans attempted several times to piece together a larger force to drive away the Carthaginian raiders, but Hannibal's superior tactics defeated them over and over. Finally, as winter approached, the Romans gave in. They had done everything they could to resist even moderate peace talks, mobilizing the entire male population including slaves, outlawing the word “peace”, and banning public crying while limited mourning periods to 30 days. Hannibal is noted by historians such as the Roman Livy as saying that want broke the Romans' back, but never military defeat.
The war ended very favorably to the Carthaginians, who raised up opposing cities such as Tarentum and Pisa to cow Roman influence on the peninsula. Carthage's empire would spread as the centuries progressed, south into Africa and eastward through the Mediterranean and Black Seas, using their famous navy to establish colonies and dominance in places such as Greece, Egypt, and Palestine. As a merchant people, their influence was largely cultural with an increase of child-sacrifice seen in archeology, and their empire did not go much beyond the navigable shores. After hundreds of years of dominance, the Carthaginians would eventually fall to invading Vandals, whose King Genseric would establish his capital and center of his state religion of Arian Christianity there in 439.
In reality, Hamilcar never killed Hanno II. In the Second Punic War, Hanno would sway the Carthaginians away from sending reinforcements, and Hannibal would never take Rome itself. He marched on Rome in 211 BC, but the attack was temporary and largely propagandist. For the next thirteen years after Cannae, Hannibal would fight a losing war in Italy before being recalled to defend Carthage from a Roman invasion force under Scipio Africanus, who would defeat him at the Battle of Zama.