Titus Livius (Livy), The History of Rome, Book 9
Rev. Canon Roberts, Ed.

39. The following day, after fresh auspices had been taken, the Dictator was invested with his official powers. He took command of the legions which were raised during the scare connected with the expedition through the Ciminian forest, and led them to Longula. [2] Here he took over the consul's troops, and with the united force went into the field. The enemy showed no disposition to shirk battle, but while the two armies stood facing each other fully prepared for action, yet neither anxious to begin, they were overtaken by night. [3] Their standing camps were within a short distance of each other, and for some days they remained [4??] quiet, not, however, through any distrust of their own strength or any feeling of contempt for the enemy.

[5] Meantime the Romans were meeting with success in Etruria, for in an engagement with the Umbrians the enemy were unable to keep up the fight with the spirit with which they began it, and, without any great loss, were completely routed. An engagement also took place at Lake Vadimonis, where the Etruscans had concentrated an army raised under a lex sacrata,¹ in which each man chose his comrade. [6] As their army was more numerous than any they had previously raised, so they exhibited a higher courage than they had ever shown before. So savage was the feeling on both sides that, without discharging a single missile, they began the fight at once with swords. [7] The fury displayed in the combat, which long hung in the balance, was such that it seemed as though it was not the Etruscans who had been so often defeated that we were fighting with, but some new, unknown people. There was not the slightest sign of yielding anywhere; as the men in the first line fell, those in the second took their places, to defend the standards. [8] At length the last reserves had to be brought up, and to such an extremity of toil and danger had matters come that the Roman cavalry dismounted, and, leaving their horses in charge, made their way over piles of armour and heaps of slain to the front ranks of the infantry. [9] They appeared like a fresh army amongst the exhausted combatants, and at once threw the Etruscan standards into confusion. [10] The rest of the men, worn out as they were, nevertheless followed up the cavalry attack, and at last broke through the enemy's ranks. Their determined resistance was now overcome, and when once their maniples began to give way, they soon took to actual flight.

[11] That day broke for the first time the power of the Etruscans after their long-continued and abundant prosperity. The main strength of their army was left on the field, and their camp was taken and plundered.