Aeneas Tacticus 18.13-19: A plot that goes nowhere with a lot of effort

13. An agreement was once made to betray Teos, a Ionian city of considerable size, to Temenus the Rhodian, with the complicity of the sentinel at the gate. Among other arrangements they fixed upon a dark night when there would be no moon, on which the sentinel was to open the gates and Temenus was to enter with his mercenaries. 14. During the day before the night when the attempt was due, a man waited by the sentinel; when it grew late and the guards were being posted along the wall, and the gates were about to be shut, this man slipped out in the gathering darkness, after making fast one end of a ball of spun cord which would stand a good strain. 15. Unrolling the ball as he went, he made his way to a spot five stades from the city, where the attacking force had arranged to meet him. 16. When the general came round to shut the gates and as usual gave the sentinel the bolt to insert, he took it and, without making a noise or attracting notice, cut a notch in it with a file or a chisel, so that a thread would catch; next he slipped a loop round the bolt and let it down with the thread attached to it; and then, after shaking the bar to show the general that the gate was secure, kept quiet. 17. After a time he pulled up the bolt and tied the end of the cord to his person, so that, if by any chance he fell asleep, he would be roused by a pull of the cord. 18. Meanwhile Temenus was ready waiting, with the force which was to make the attack, at the place agreed upon with the man who had the ball of cord. It had been arranged that Temenus should go to the place and pull the cord: 19. and if the sentinel had succeeded in making all ready, he was to have fastened to the cord a piece of wool and let it go; on seeing this, Temenus was to have made a rush for the gates. But the sentinel was unsuccessful in his enterprise, he let the cord go with nothing attached to it, so that Temenus had plenty of time to escape unobserved: they had, after all, noticed during the night in the city that the cord was there, and so it was impossible to proceed further.