According to Livy, no special measures were taken in Rome, and the levy "was not larger than had been usual in ordinary campaigns." The Gauls marched on Rome so quickly that "Rome was thunderstruck by the swiftness at which they moved, which is shown both by the haste in mustering the army, as if it were meeting a spur-of-the moment emergency and the difficulty in getting any further than the eleventh milestone." The Romans presumably were outnumbered. They did not set up camp or build a defensive rampart and they did not divine the gods, as they were supposed to. They extended the wings to avoid being outflanked, but that made their line so thin and weakened that the centre could hardly be kept together. They placed the reserves on a hill on the right. Brennus, the Senone chieftain, suspected that to be a ruse and that the reservists would attack him from the rear while he was fighting the Roman army in the plain. He therefore attacked the hill.