Battle of Lake Trasimene The Battle of Lake Trasimene ( June 21 , 217 BC , April on the Julian calendar ) was a major battle in the Second Punic War . The Carthaginians under Hannibal defeated the Romans under the consul Gaius Flaminius . The battle is one of the largest and most successful ambush es in military history . Prelude . The Romans , greatly alarmed and dismayed by Tiberius Sempronius Longus ’ defeat at Trebia , immediately made plans to counter the new threat from the north . Sempronius returned to Rome and the Roman Senate resolved to elect new consuls the following year in 217 BC . The new consuls were Gnaeus Servilius Geminus and Gaius Flaminius , the latter under threat with recall from the Senate for leaving Rome without carrying out the proper rituals upon being elected consul . The Senate commissioned Servilius to replace Publius Cornelius Scipio and take command of his army , while Flaminius was appointed to lead what remained of Sempronius ’ s army . Since both armies had been weakened by the defeat at Trebia , four new legions were raised . These new forces , together with the remains of the former army , were divided between the two consuls . After the battles of Ticinus and Trebia , Flaminius ' army turned south to prepare a defence near Rome itself . Hannibal immediately followed , but marched faster and soon passed the Roman army . Flaminius was forced to increase the speed of his march in order to bring Hannibal to battle before reaching the city . Another force under Servilius was due to join Flaminius . Before this could happen , Hannibal lured Gaius Flaminius ' force into a pitched battle , by devastating the area Flaminius had been sent to protect . Polybius wrote that Hannibal calculated that he could draw out Flaminius into battle and that " no sooner had he left the neighbourhood of Faesulae , and , advancing a short way beyond the Roman camp , made a raid upon the neighbouring country , then Flaminius became excited , and enraged at the idea that he was despised by the enemy : and as the devastation of the country went on , and he saw from the smoke that rose in every direction that the work of destruction was proceeding , he could not patiently endure the sight . " At the same time , Hannibal tried to sever the allegiance of Rome ’ s allies , by proving that the Republic was powerless to protect them . However , Flaminius remained passively encamped at Arretium . Unable to goad Flaminius into battle , Hannibal marched boldly around his opponent ’ s left flank and effectively cut Flaminius off from Rome ( thereby executing the earliest recorded deliberate turning movement in military history ) . Still , Flaminius stubbornly kept his army in camp . Hannibal decided to march on Apulia , hoping that Flaminius might follow him to a battlefield of his own choosing . Flaminius , eager to exact revenge for the devastation of the countryside , and facing increasing political criticism from Rome , finally marched against Hannibal . Flaminius , like Sempronius , was impetuous , overconfident , and lacking in self - control . His advisors suggested that he send only a cavalry detachment to harass the Carthaginians and prevent them from laying waste to any more of the country , while reserving his main force until the other consul , Servilius , arrived with his army . However , it proved impossible to argue with the rash Flaminius . Livy wrote that " Though every other person in the council advised safe rather than showy measures , urging that he should wait for his colleague , in order that joining their armies , they might carry on the war with united courage and counsels . . . Flaminius , in a fury . . . gave out the signal for marching for battle . " Battle . Tactical disposition . As Hannibal passed Lake Trasimene , he came to a place very suitable for an ambush , and hearing that Flaminius had broken camp and was pursuing him , made preparations for the impending battle . To the north was a series of heavily forested hills where the Malpasso Road passed along the north side of Lake Trasimene . Along the hill - bordered skirts of the lake , Hannibal camped where he was in full view of anyone entering the northern defile , and spent the night arranging his troops for battle . Below the camp , he placed his heavy infantry ( Iberians , Celts , and Africans ) upon a slight elevation . Here , they had ample ground from which they could charge down upon the head of the Roman column on the left flank , when it should reach the position . His cavalry and Gallic infantry were concealed in the hills in the depth of the wooded valley from which the Romans would first enter , so that they could quickly sally out and close the entrance , blocking the retreat route of the Romans . Then he posted his light troops at intervals along the height overlooking the plain , with orders to keep well hidden in the woods until signalled to attack . In addition , the night before the battle commenced , Hannibal ordered his men to light campfires on the hills of Tuoro , at a considerable distance , so as to convince the Romans that his forces were further away than they actually were . Events . The morning of June 21 , the Roman troops marched eastward along the road running near the northern edge of the lake . Eager for battle , Flaminius pushed his men hard and hurried up the column in the rear . Hannibal then sent a small skirmish force to draw the vanguard away from the front of the line , in order to split the Roman forces . Once all the Romans had at last marched through the foggy , narrow defile and entered the plains skirting the lake , trumpets were blown , signalling the general attack . The Carthaginian cavalry and infantry swept down from their concealed positions in the surrounding hills , blocked the road and engaged the unsuspecting Romans from three sides . Surprised and outmaneuvered , the Romans did not have time to draw up in battle array , and were forced to fight a desperate hand - to - hand battle in open order . The Romans were quickly split into three parts . The westernmost was attacked by the Carthaginian cavalry and forced into the lake , leaving the other two groups with no way to retreat . The centre , including Flaminius , stood its ground , but was cut down by Hannibal ' s Gauls after three hours of heavy combat . In less than four hours , the Roman army was annihilated . The vanguard saw little combat and , once the disaster to their rear became obvious , fought their way through the skirmishers and out of the forest . Of the initial Roman force of about 30 , 000 , about 15 , 000 were either killed in battle or drowned while trying to escape into the lake — including Flaminius himself , who was slain by the Gaul Ducarius . Another 10 , 000 are reported to have made their way back to Rome by various means , and the rest were captured . Hannibal ' s losses were 2 , 500 , plus " many " who died of their wounds . About 6 , 000 Romans escaped , under the cover of fog , only to be captured by Maharbal the following day . Both Livy and Polybius wrote that Maharbal promised safe passage ( " with a garment apiece " ) if they surrendered their weapons and armour , but Hannibal had them sold into slavery irrespective of the promise made . The disaster for Rome did not end there . Within a day or two , a reinforcement force of 4 , 000 under the propraetor Gaius Centenius was intercepted and destroyed . Aftermath . Hannibal , emerging from another brilliant victory , had successfully planned and executed the greatest ambush in history . News of the defeat caused a panic in Rome . Quintus Fabius Maximus was elected dictator by the Roman Assembly and adopted the " " Fabian strategy " " of avoiding pitched conflict , relying instead on low - level harassment to wear the invader down , until Rome could rebuild its military strength . Hannibal was left largely free to ravage Apulia for the next year , until the Romans ended the dictatorship and elected Paullus and Varro as consuls . The result would be the Battle of Cannae , the worst defeat the Romans would suffer throughout the Second Punic War .