No plan was ever more successful.  In haste, the consul followed the line of march of the enemy, who passed by Arezzo and moved slowly through the rich valley of the Chiana towards Perugia.  He overtook him in the district of Cortona, where Hannibal, accurately informed of his antagonist’s march, had had full time to select his field of battle—­a narrow defile between two steep mountain walls, closed at its outlet by a high hill, and at its entrance by the Trasimene lake.  With the flower of his infantry he barred the outlet; the light troops and the cavalry placed themselves in concealment on either side.  The Roman columns advanced without hesitation into the unoccupied pass; the thick morning mist concealed from them the position of the enemy.  As the head of the Roman line approached the hill, Hannibal gave the signal for battle; the cavalry, advancing behind the heights, closed the entrance of the pass, and at the same time the mist rolling away revealed the Phoenician arms everywhere along the crests on the right and left.  There was no battle; it was a mere rout.  Those that remained outside of the defile were driven by the cavalry into the lake.  The main body was annihilated in the pass itself almost without resistance, and most of them, including the consul himself, were cut down in the order of march.  The head of the Roman column, formed of 6000 infantry, cut their way through the infantry of the enemy, and proved once more the irresistible might of the legions; but, cut off from the rest of the army and without knowledge of its fate, they marched on at random, were surrounded on the following day, on a hill which they had occupied, by a corps of Carthaginian cavalry, and—­as the capitulation, which promised them a free retreat, was rejected by Hannibal—­were all treated as prisoners of war. 15,000 Romans had fallen, and as many were captured; in other words, the army was annihilated.  The slight Carthaginian loss—­1500 men—­again fell mainly upon the Gauls.(3) And, as if this were not enough, immediately after the battle on the Trasimene lake, the cavalry of the army of Ariminum under Gaius Centenius, 4000 strong, which Gnaeus Servilius had sent forward for the temporary support of his colleague while he himself advanced by slow marches, was likewise surrounded by the Phoenician army, and partly slain, partly made prisoners.  All Etruria was lost, and Hannibal might without hindrance march on Rome.  The Romans prepared themselves for the worst; they broke down the bridges over the Tiber, and nominated Quintus Fabius Maximus dictator to repair the walls and conduct the defence, for which an army of reserve was formed.  At the same time two new legions were summoned under arms in the room of those annihilated, and the fleet, which might become of importance in the event of a siege, was put in order.

Hannibal on the East Coast
Reorganization of the Carthaginian Army