Final answer:
At the Battle of Lake Trasimene in 217 BCE, Carthage, under General Hannibal, ambushed and defeated the Roman army, marking it as one of Rome's most significant military disasters.
Step-by-step explanation:
During the Battle of Lake Trasimene in 217 BCE, part of the Second Punic War, the Carthaginian forces led by General Hannibal Barca achieved a significant victory over the Roman army. The battle is notable for Hannibal's tactical brilliance; he conducted an ambush by hiding his men in the hills surrounding the lake. As the Roman troops marched along the lake's shore, they were trapped and could not effectively respond to the sudden attack coming from surrounding hills. This defeat was one of Rome's worst in its military history and highlighted Hannibal's skills as a military strategist, further terrifying the Romans after earlier defeats at Trebia and later at Cannae.