I am currently reading Polybius’ Histories, and I have finally gotten to the part where he describes the events during the Second Punic War. Last night I read his account of the battle of Lake TRasimene in 217 B.C.
Trasimene was not the first of the great disasters to befall the Romans in the Second Punic War, but it was the first that really threw the Roman people into a panic. The Romans had been defeated and lost an army at the Battle of the Trebia
in December, 218 B.C. the Romans had reacted to that loss by raising another army to face Hannibal led by the Consuls for 217 B.C. Gnaeus Servilius Geminus and Gaius Flaminius. It was Flaminius who was in command of the army at Trasimene; Servilius had been sent to Spain to take command of the army there. Polybius does not have a very high opinion of Flaminius, saying that “Flaminius was a thorough mob-courtier and demagogue, with no talent for the practical conduct of war and exceedingly self-confident.â€1 He essentially blames the stupidly and vanity of Flaminius combined with the genius of Hannibal for the defeat at Lake Trasimene.The opposing forces were not too unevenly matched; the Carthaginians field about 50,000 troops while the Romans had 40,000. These odds did not guarantee a Carthaginian victory.
Hannibal was indeed a great general, one of the greatest the world has ever seen despite the fact that he was eventually defeated. He chose his battlefields well and the battlefield at Lake Trasimene was no exception. The battlefield he chose had a range of hills on one side of the battlefield and the lake on the other with a gully or defile among the hills. He placed his light infantry and cavalry on both flanks and stationed his heavy infantry to block the main Roman force. It also helped Hannibal that the day of the battle was exceptionally foggy.2 The Romans walked right into Hannibalâ€™s trap. As the lead Roman troops were engaged, the Carthaginian troops on the flank enveloped the Roman army and trapped it against the lake. Once the Romans were trapped, the course of the battle was almost foreordained. The Carthaginians pushed the Romans against the lake and essentially slaughtered them. Of the Roman force of 40,000 only about 6,000 escaped and that, only because they were not fully into the trap when it was sprung and managed to fight their way out. However, they were unable to help their comrades and had to watch helplessly as the rest of the Roman army was destroyed.
The Romans were defeated because of a single envelopment, meaning that one of their flanks was attacked. The phalangeal formation used by ancient armies made a flank attack even more dangerous than in contemporary warfare where they are still the most dangerous attack a unit can face. A phalanx was tight packed mass of men who all faced front, the nature of the formation meant that they could not easily turn to face attackers from the sides or rear. The Romans would eventually solve this problem by redesigning their formation into the manipular and later cohort formation of their legions. That did not help them in the Second Punic War though.
The Battle of Lake Trasimene was the first disaster in the Second Punic War in which the Romans lost an entire army; it would not be the last though. A few years later Hannibal would repeat the performance of Trasimene at Cannae. He would scourge the Italian Peninsula for fifteen years until Publius Cornelius Scipio took the fight to Africa and defeated Hannibal at the battle of Zama, ending the Second Punic War.
1. Polybius, The Histories , 3:82,3
2. Ibid. 3:84,1