Twenty-three years elapsed between the First and Second Punic Wars. The power of Carthage, though crippled, was not destroyed; and Hamilcar returned home, burning with hatred against Rome, and determined to renew the war upon a favorable opportunity. But a new and terrible danger threatened Carthage upon her own soil. The mercenary troops, who had been transported from Sicily to Africa at the conclusion of the war, being unable to obtain their arrears of pay, rose in open mutiny. Their leaders were Spendius, a runaway Campanian slave, and Matho, a Libyan. They were quickly joined by the native Libyans, and brought Carthage almost to the brink of destruction. They laid waste the whole country with fire and sword, made themselves masters of all the towns except the capital, and committed the most frightful atrocities. Carthage owed her safety to the genius and abilities of Hamilcar. The struggle was fierce and sanguinary, but was at length brought to a successful issue, after it had lasted more than three years, by the destruction of all the mercenaries. It was called the War without Peace, or the Inexpiable War (B.C. 238).

The Romans availed themselves of the exhausted condition of Carthage to demand from her the islands of Sardinia and Corsica, and the payment of a farther sum of 1200 talents. The mercenary troops in Sardinia, who had also revolted, had applied to Rome for assistance; and the Senate menaced her rival with war unless she complied with these unjust demands. Resistance was impossible, and Sardinia and Corsica were now formed into a Roman province, governed, like Sicily, by a PrÆtor sent annually from Rome (B.C. 238). This act of robbery added fresh fuel to the implacable animosity of Hamilcar against the grasping Republic. He now departed for Spain, where for many years he steadily worked to lay the foundation of a new empire, which might not only compensate for the loss of Sicily and Sardinia, but enable him at some time to renew hostilities against Rome.

Rome was now at peace, and in B.C. 235 the Temple of Janus, which had remained open since the days of Numa, was closed for a second time. Two new tribes were added to the Roman territory, thus making their total number thirty-five.

The Temple of Janus did not long remain closed. The Illyrians, who dwelt near the head of the Adriatic upon its eastern side, were a nation of pirates, who ravaged the coasts of this sea. The Senate having sent embassadors to the Illyrian queen, Teuta, to complain of these outrages, she not only refused to attend to their complaints, but caused one of the embassadors to be murdered. War was straightway declared, and a Roman army for the first time crossed the Adriatic (B.C. 229). Demetrius of Pharos, an unprincipled Greek, who was the chief counselor of Teuta, deserted his mistress, and surrendered to the Romans the important island of Corcyra. Teuta was obliged to yield to the Romans every thing they demanded, and promised that the Illyrians should not appear south of Lissa with more than two vessels. The suppression of piracy in the Adriatic was hailed with gratitude by the Grecian states, and deserves notice as the first occasion upon which the Romans were brought into immediate contact with Greece. The Consul Postumius, who had wintered in Illyria, sent envoys to Athens, Corinth, and other Grecian cities, to explain what had been done. The envoys were received with honor, and thanks were returned to Rome (B.C. 228).

The Romans had scarcely brought this trifling war to an end when they became involved in a formidable struggle with their old enemies the Gauls. Since the conquest of the Senones in B.C. 289, and of the Boii in B.C. 283, the Gauls had remained quiet. The Romans had founded the colony of Sena after the subjugation of the Senones; and in B.C. 268 they had still farther strengthened their dominion in those parts by founding the colony of Ariminum. But the greater part of the soil from which the Senones were ejected became Public Land. In B.C. 232 the Tribune C. Flaminius carried an Agrarian Law to the effect that this portion of the public land, known by the name of the "Gallic Land,"[30] should be distributed among the poorer citizens. This alarmed the Boii, who dwelt upon the borders of this district. They invoked the assistance of the powerful tribe of the Insubres, and being joined by them, as well as by large bodies of Gauls from beyond the Alps, they set out for Rome.

All Italy was in alarm. The Romans dreaded a repetition of the disaster of the Allia. The Sibylline Books being consulted, declared that Rome must be twice occupied by a foreign foe; whereupon the Senate ordered that two Gauls and a Grecian woman should be buried alive in the forum. The allies eagerly offered men and supplies to meet a danger which was common to the whole peninsula. An army of 150,000 foot and 6000 horse was speedily raised. A decisive battle was fought near Telamon in Etruria. The Gauls were hemmed in between the armies of the two Consuls. As many as 40,000 of their men were slain, and 10,000 taken prisoners (B.C. 225). The Romans followed up their success by invading the country of the Boii, who submitted in the following year (B.C. 224).

In B.C. 223 the Romans for the first time crossed the Po, and the Consul C. Flaminius gained a brilliant victory over the Insubres. The Consuls of the next year, Cn. Cornelius Scipio and M. Claudius Marcellus, continued the war against the Insubres, who called in to their aid a fresh body of Transalpine Gauls. Marcellus slew with his own hand Viridomarus, the chief of the Insubrian Gauls, and thus gained the third Spolia Opima. At the same time Scipio took Mediolanum (Milan), the chief town of the Insubres. This people now submitted without conditions, and the war was brought to an end. To secure their recent conquests, the Romans determined to plant two powerful Latin colonies at Placentia and Cremona, on opposite banks of the Po. These were founded in B.C. 218, and consisted each of 6000 men. The Via Flaminia, a road constructed by C. Flaminius during his consulship (B.C. 220), from Rome to Ariminum, secured the communication with the north of Italy.

While the Romans were engaged in the Gallic wars, the traitor Demetrius of Pharos had usurped the chief power in Illyria, and had ventured upon many acts of piracy. In B.C. 219 the Consul L. Æmilius Paullus crossed the Adriatic, and soon brought this second Illyrian war to an end. Demetrius fled to Philip of Macedon, where we shall shortly afterward see him prompting this king to make war against Rome. The greater part of Illyria was restored to the native chiefs; but the Romans retained possession of Corcyra, and of the important towns of Apollonia and Oricum on the coast.

Meanwhile Hamilcar had been steadily pursuing his conquests in Spain. The subjugation of this country was only a means to an end. His great object, as already stated, was to obtain the means of attacking, and, if possible, crushing that hated rival who had robbed his country of Sicily, Sardinia, and Corsica. His implacable animosity against Rome is shown by the well-known tale that, when he crossed over to Spain in B.C. 235, taking with him his son Hannibal, then only nine years old, he made him swear at the altar eternal hostility to Rome. During the eight years that Hamilcar continued in Spain he carried the Carthaginian arms into the heart of the country. While he conquered several states in war, he gained over others by negotiation, and availed himself of their services as allies or mercenaries. He fell in battle in B.C. 229, and was succeeded in the command by his son-in-law Hasdrubal. His plans were ably carried out by his successor. The conciliatory manners of Hasdrubal gained him the affections of the Spaniards; and he consolidated the Carthaginian empire in Spain by the foundation of New Carthage, now Cartagena, in a situation admirably chosen on account of its excellent harbor and easy communication with Africa, as well as from its proximity to the silver mines, which supplied him with the means of paying his troops. The conduct of his warlike enterprises was intrusted to the youthful Hannibal, who had been trained in arms under the eye of his father, and who already displayed that ability for war which made him one of the most celebrated generals in ancient or modern times. The successes of Hamilcar and Hasdrubal could not fail to attract the notice of the Romans, and in B.C. 227 they concluded a treaty with the latter, by which the River Iberus (Ebro) was fixed as the northern boundary of the Carthaginian empire in Spain.

Hasdrubal was assassinated in B.C. 221 by a slave whose master he had put to death. Hannibal had now acquired such a remarkable ascendency over the army that the soldiers unanimously proclaimed him commander-in-chief, and the government at Carthage hastened to ratify an appointment which they had not, in fact, the power to prevent. Hannibal was at this time in the 26th year of his age. There can be no doubt that he already looked forward to the invasion and conquest of Italy as the goal of his ambition; but it was necessary for him first to complete the work which had been so ably begun by his two predecessors, and to establish the Carthaginian power as firmly as possible in Spain. This he accomplished in two campaigns, in the course of which he brought all the nations south of the Iberus into subjection to Carthage.

Early in the spring of B.C. 219 he proceeded to lay siege to Saguntum, a city of Greek origin, founded by the Zacynthians. Though situated to the south of the Iberus, and therefore not included under the protection of the treaty between Hasdrubal and the Romans, Sagantum had concluded an alliance with the latter people. There could be little doubt, therefore, that an attack upon this city would inevitably bring on a war with Rome; but for this Hannibal was prepared, or, rather, it was unquestionably his real object. The immediate pretext of his invasion was the same of which the Romans so often availed themselves—some injury inflicted by the Saguntines upon one of the neighboring tribes, who invoked the assistance of Hannibal. But the resistance of the city was long and desperate, and it was not till after a siege of nearly eight months that he made himself master of the place. During all this period the Romans sent no assistance to their allies. They had, indeed, as soon as they heard of the siege, dispatched embassadors to Hannibal, but he referred them for an answer to the government at home, and they could obtain no satisfaction from the Carthaginians, in whose councils the war-party had now a decided predominance. A second embassy was sent, after the fall of Saguntum, to demand the surrender of Hannibal, in atonement for the breach of the treaty. After much discussion, Q. Fabius, one of the Roman embassadors, holding up a fold of his toga, said, "I carry here peace and war; choose ye which ye will." "Give us which you will," was the reply. "Then take war," said Fabius, letting fall his toga. "We accept the gift," cried the Senators of Carthage. Thus commenced the Second Punic War.