Titus Livius (Livy), The History of Rome, Book 10
Rev. Canon Roberts, Ed.

42. The consul was at first unaware of what was going on, and was anxious to recall his troops, for the sun was now rapidly sinking and the approaching night was making every place suspicious and dangerous, even for victorious troops. [2] After he had ridden forward some distance he saw that the camp on his right hand had been captured, and he heard at the same time the mingled clamour of shouts and groans arising in the direction of the city on his left; just then the fighting at the gate was going on. [3] As he approached more closely he saw his men on the walls and recognised that the position was no longer doubtful, since by the reckless daring of a few the opportunity for a brilliant success had been won. He at once ordered the troops whom he had recalled to be brought up and prepared for a regular attack on the city. [4] Those who were within bivouacked near the gate as night was approaching, and during the night the place was evacuated by the enemy. [5] The Samnite losses during the day amounted to 20,340 killed and 3870 made prisoners, whilst 97 standards were taken. [6] It is noticed in the histories that hardly any other general ever appeared in such high spirits during the battle, either owing to his fearless temperament or to the confidence he felt in his final success. [7] It was this dauntless and resolute character which prevented him from abandoning all idea of fighting when the omens were challenged. It was this, too, that made him in the very crisis of the struggle, at the moment when it is customary to vow temples to the gods, make a vow to Jupiter Victor that if he routed the legions of the enemy he would offer him a cup of sweetened wine before he drank anything stronger himself. This vow was acceptable to the gods and they changed the omens into favourable ones.