The outer _enceinte_ was so weak that it was intended that the main defence should be in the network of streets. Special preparations were thought out for the right-centre of the north front, where the walls are pierced by the ravine of a winter torrent of intermittent flow, called the Retiro. The point where it made its passage under the _enceinte_ through a portcullis was the lowest place in the front, the walls sinking down as they followed the outline of the ravine. Wherefore palisades were planted outside the portcullis, entanglements behind it, and all the houses looking down on the torrent bed within the walls were prepared with loopholes commanding its course[109]. There was ample time for work, for while the first certain news that the French were coming arrived in November, the enemy did not actually appear before the walls till December 20. By that time much had been done, though the balance was only completed in haste after the siege had begun. [108] This was the famous knight who, holding the place for King Sancho IV in 1294, refused to surrender it when the Moors brought his son, captured in a skirmish, before the walls, and threatened to behead him if his father refused to capitulate. Guzman would not yield, saw his son slain, and successfully maintained the fortress. [109] For these precautions, the work of Captain Charles Smith, R.E., see the anonymous _Defence of Tarifa_ (p. 62), and Napier, iv. pp. 59-60. The long delay of the enemy was caused by the abominable condition of the roads of the district--the same that had given Graham and La Peña so much trouble in February 1811[110]: moreover, any considerable concentration of troops in southern Andalusia raised a food problem for Soult. The region round Tarifa is very thinly inhabited, and it was clear that, if a large army were collected, it would have to carry its provisions with it, and secure its communication with its base, under pain of falling into starvation within a few days. Heavy guns abounded in the Cadiz lines, and Soult had no trouble in selecting a siege-train of sixteen pieces from them: but their transport and that of their ammunition was a serious problem. To complete the train no less than 500 horses had to be requisitioned from the field artillery and military wagons of the 1st Corps. While it was being collected, Victor moved forward to Vejer, near the coast, half-way between Cadiz and Tarifa, with 2,000 men, in order to clear the country-side from the guerrillero bands, who made survey of the roads difficult and dangerous. Under cover of escorts furnished by him, several intelligence officers inspected the possible routes: there were two, both passing through the mountainous tract between the sea and the lagoon of La Janda (which had given Graham so much trouble in the last spring). One came down to the waterside at the chapel of Virgen de la Luz, only three miles from Tarifa, but was reported to be a mere mule-track.