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

32. Q. Fabius and P. Decius were succeeded in the consulship by L. Postumius Megellus and M. Atilius Regulus. [2] Samnium was assigned to both of them as the field of operations in consequence of information received that three armies had been raised there, one being destined for Etruria, another was to ravage Campania, and the third was intended for the defence of their frontiers. [3] Illness kept Postumius in Rome, but Atilius marched out at once in accordance with the senate's instructions, with the view of surprising the Samnite armies before they had started on their expeditions. [4] He met the enemy, as though they had had a previous understanding, at a point where he himself was stopped from entering the Samnite country and at the same time barred any movement on their part towards Roman territory or the peaceable lands of her allies. [5] The two camps confronted each other, and the Samnites, with the recklessness that comes of despair, ventured upon an enterprise which the Romans, who had been so often victorious, would hardly have undertaken, namely an attack on the enemy's camp. Their daring attempt did not achieve its end, but it was not altogether fruitless. [6] During a great part of the day there had been so dense a fog that it was not only impossible to see anything beyond the rampart, but even people who were together were unable to see each other. [7] The Samnites, relying on their movements being concealed, came on in the dim twilight —what light there was being obscured by the fog —and [8] reached the outpost in front of the gate who were keeping a careless look-out, and who being thus attacked unawares had neither the strength nor the courage to offer any resistance. After disposing of the guard they entered the camp through the decuman gate and got [9??] possession of the quaestor's tent, ¹ the quaestor, L. Opimius Pansa, being killed. Then there was a general call to arms.