Ab urbe condita

Titus Livius (Livy)

Livy. History of Rome, Volumes 1-2. Roberts, Canon, Rev, translator. London, New York: J. M. Dent and Sons; E. P. Dutton and Co., 1912.

For some time Manlius was in doubt whether the moment had not come for calling up the triarii, but judging it better for them to be kept fresh till the final crisis of the battle, he gave orders for the accensi at the extreme rear to advance to the front.

When they came up, the Latins, taking them for the opposing triarii, instantly called up their own. In the desperate struggle they had tired themselves out and broken or blunted their spears, but as they were still driving the enemy back by main force, they imagined that the battle was decided and that they had reached their last line.