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.
They found it blocked by a huge barricade of felled trees with great masses of rock piled against them. No sooner did they become aware of the enemy's stratagem than his outposts showed themselves on the heights above the pass.
A hasty retreat was made, and they proceeded to retrace their steps by the way they had come when they discovered that this pass also had its own barricade and armed men on the heights above. Then without any order being given they called a halt. Their senses were dazed and stupefied and a strange numbness seized their limbs.
Each gazed at his neighbour, thinking him more in possession of his senses and judgment than himself. For a long time they stood silent and motionless, then they saw the consuls' tents being set up and some of the men getting their entrenching tools ready.