After putting down a rebellion among Carthaginian mercenaries in 238 BC, Hamilcar gained large personal power.  And with his newly found power, he began the conquest of Spain in 237 BC and began planning an attack on Rome with Spain as his base.  Hamilcar worked on his master plan for the attack on Rome for the remainder of his life.  This 'master plan' became the bases that Hannibal used in his campaign against Rome some 10 years after his father's death.