Lingering mutual animosity and renewed tensions along their borderlands led to the Second Punic War (218-201 BC), which involved factions from across the western and eastern Mediterranean. The war is marked by Hannibal's surprising overland journey to Rome, particularly his costly and strategically bold crossing of the Alps. His entrance into northern Italy was followed by his reinforcement by Gaulish allies and crushing victories over Roman armies in the Battle of the Trebia and the giant ambush at Trasimene. Against his skill on the battlefield the Romans employed the Fabian strategy, which resorted to skirmishes in lieu of direct engagement, with the aim delaying and gradually weakening his forces. While effective, this approach was politically unpopular, as it ran contrary to traditional military strategy. The Romans thus resorted to another major field battle at Cannae, but despite their superior numbers, suffered a crushing defeat, suffering, it is said, 60000 casualties.