47. It is about forty Roman miles from the Durance at Mont Dauphin to the summit of the Col de la Traversette, and also about forty from the Durance at La Bréole to the summit of the Col d’Argentière. Hannibal, however, deviated from whatever route he meant to take. Polybios says (iii. 52. 3–8) that Hannibal was led into a dangerous gorge by the treachery of some guides he had engaged two days before, their object being to draw him into a position where he could be attacked on every side from higher ground. (Polybios has not made it clear why these guides were engaged: he states in iii. 44. 5, 7, 48. 11 that guides had come over from Italy to meet Hannibal at the crossing of the Rhone--perhaps they were all killed at the first gorge.) Livy (xxi. 35) suggests that instead of following the guides, Hannibal took a line of his own as soon as he lost confidence in them, and thus went astray into impassable places, _per invia pleraque et errores_. His actual march must have been a good deal longer than his intended route. * * * * * 48. According to Polybios (iii. 54. 1–3) Hannibal made a speech at the summit of the pass, telling the soldiers that the worst part of their march was done; and he not only pointed to the plain of the Po spread out before them, but indicated the position (_topos_) of Rome itself. As he was a good 300 miles from Rome, he could not have managed this unless he used a map. Herodotos says (v. 49. 1, 5) that Aristagoras used a map to show the route, when he was trying to induce the Spartans to march through Asia Minor in 500 B.C.; and Hannibal may likewise have used a map in 218 B.C., when maps were commoner. No doubt, a map could not be seen except by men who were close by, but a speech could not be heard by men who were far off; and I conceive that when Hannibal (or any other general) addressed an army of 20,000 or 30,000 men, he relied on those who heard him to convey the substance of his speech to those who could not hear. The more important officers would be standing near the general, and they would see the map and tell the others about it.