Unrest within the city government in Saguntum led to the assassination of the supporters of Carthage in 219 BC. Hannibal responded by laying siege and eventually took over the Iberian city with diplomatic ties to Rome. It was on the boundary between the two empires, where the liberty of the city should be preserved, as agreed between Rome and Hasdrubal the Fair. This triggered the Second Punic War between Hannibal and the Carthaginians and the Roman Republic in 218 BC. This is a category of hannibal coins.
Hannibal began to move through the Alps and invaded northern Italy in Spring 218 BC, surprising the Romans and gathering support of the Gallic tribes along the way. The Roman consul, Publius Cornelius Scipio, moved to block Hannibal at Ticinus in November, but was defeated and wounded in the process. The Romans were forced to cede the area to the Carthaginians, which led to the Gauls and Ligurians to side with Hannibal as well, bringing his forces to around 40,000.
The Romans responded by ordering consul Tiberius Sempronius Longus to fortify Placentia and Hannibal set out to intercept before the two Roman armies could join. He couldn’t get there in time, so he decided to engage the armies strategically. In the dead of night, he positioned his forces to flank the two armies and his brother, Mago, launched an ambush after Hannibal and his cavalry engaged and lured Sempronius out of camp. Hannibal’s strategy worked and the Romans were crushed during the Battle of the Trebia on December 18, 218 BC, with the Carthaginians only suffering light losses to the Roman’s 20,000+.
The Romans elected two new consuls in 217 BC, hoping to come up with a strategy to deal with Hannibal and his growing army. Gnaeus Servilius Geminus replaced Scipio and Gaius Flaminius replaced Sempronius. Flaminius raised some new legions and retreated to a more defensible position near Rome. Hannibal learned of the plans and followed, moving faster than the Romans and passing them. The Carthaginians devastated the countryside along the way to get Roman allies to switch sides and to bait the Romans into battle. Flaminius didn’t bite, so Hannibal maneuvered around him, cutting him off from Rome. The Romans were furious about the invasion, leaving Flaminius no choice.
When Hannibal heard the army was on the move, he positioned his troops around Lake Trasimene. The way to the lake was through a narrow passage that opened into a plain to the west. The north was wooded hills and the lake was to the south. Hannibal made a token camp within sight of the passage as a ruse. The heavy infantry were hidden west of the camp and the light infantry were in the wooded hills. Further west were the Gallic forces and cavalry in a hidden valley. At night, Hannibal had campfires lit in the hills away from the troops to give the Romans the impression that’s where they needed to go the next day for battle.
Flaminius drove his troops hard the next day and reached the passage, despite being advised to wait until Geminus arrived with his for support. On June 24, 217 BC, Flaminius pushed forward through the passage. Hannibal drew the vanguard away with skirmishers as the entire Roman army entered the open plain. The Carthaginians rode in from their hidden positions in the wooded hills and the valley, while the cavalry rode in and blocked the exit. The Romans were caught completely by surprised as they were surrounded and split into three groups, unable to get into formation.
The Carthaginian cavalry forced the western group to the lake. The Gallic forces took on Flaminius and the center group, killing him along with most of his troops within the first three hours of the battle. The vanguard finally managed to break through and escape, but the Battle of Lake Trasimene saw 15,000 Roman casualties to the Carthaginian 2,500 and allowing Hannibal to make his way through Italy all of the following year. In terms of numbers, the ambush at Trasimene remains the largest in military history.