On arriving at the bridge of Facinas and the village of Bolonia, ten miles outside Tarifa, La Peña had to make up his mind whether he would march against the rear of the French lines before Cadiz by the track nearer to the coast, which passes through Vejer de la Frontera, Conil, and Chiclana, or by the inland road through the mountains, which runs past Casas Viejas to Medina Sidonia. The two roads at their bifurcation are separated by the long lagoon of La Janda, a very shallow sheet of water, seven miles long, which nearly dries up in summer, but was at this moment full to overflowing from spring rains[142]. To take the inland route across the mountains was by far the better course. The road was not good, but if the Allies could reach Medina Sidonia with their army intact, Victor would be forced to come out and attack them, at a great distance from his Lines. For it would be practically impossible for the Marshal to allow La Peña and Graham to establish themselves at Medina, in the rear of his head quarters, and backed by the Sierra de Jerez, from whose skirts they could send out as many detachments as they pleased, to cut the communication between Seville and the Lines. There was little danger of being taken in the rear by troops sent by the distant Sebastiani, whose nearest forces were at Marbella, eighty miles away, and whose attention was at this moment fully taken up by the local guerrilleros, who had been turned loose on him. Indeed, Sebastiani for some time thought that the expedition was directed against himself, and was preparing to concentrate and take the defensive. The only drawbacks to the Medina Sidonia route were there would be no chance of communicating along it with the garrison of Cadiz, and that the question of provisions might grow serious if the campaign were protracted, for the region was barren and the army ill provided with transport. But a few days would settle the affair--Victor would be compelled to come out at once and fight, with every man that he could bring, and while he was engaged at Medina, there would be nothing to prevent the 7,000 Spaniards in Cadiz from crossing the harbour and destroying the ill-garrisoned Lines. This in itself, even if the Allies failed to hold back the Marshal, would have an immense effect all over Andalusia[143]. [142] I do not know these roads, nor the field of Barrosa, but Colonel Churcher, of the Royal Irish Fusiliers, who is well acquainted with them, tells me that the track (five miles inland from the coast) marked on the British staff map of 1810, from Bolonia to Vejer, is no proper road at all, and unfit for wheeled traffic to this day; while the Tarifa-Medina Sidonia road is bad, but can carry vehicles. He tells me that he has actually crossed the Laguna de la Janda at its centre in dry weather, so shallow does it become. [143] There is a good note on the pros and cons of the two routes in Schepeler, i. 161.