Initially Corculum had enough support in the senate to reject Cato's proposal. It seems that in 152 he headed an embassy sent to mediate between Carthage and Massinissa. While blaming the former for their military built-up, he forced the latter to withdraw from some of the territories he had conquered, which temporarily removed the threat of a war in the area. Corculum's influence can also be measured by the fact that in 150 he was chosen "pontifex maximus"—the most important priesthood. Carthage nonetheless attacked the army of Massinissa later in 150, thus breaching the treaty of 201, which stated that Carthage could not wage war without Rome's assent; Carthage therefore gave "casus belli" to Rome, which finally declared war in the beginning of 149.