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.