A history of the Peninsular War, Vol. 3, Sep. 1809-Dec. 1810

by Charles Oman

It was fortunate that Portugal was a well-wooded country: there are regions where it would be impossible to procure the immense amount of timber that was lavished on the accessories of the redoubts. All, as has been already mentioned, were palisaded; many had in addition abattis or entanglements thrown up in front of them, some way down the hillside, so as to detain the advancing enemy under fire as long as possible.

The works were divided into eight sections, the first line composed of four, the second line of three, while the eighth consisted of the inner retrenchment for purposes of embarkation, at the extreme southern point of the peninsula. Of the outer or secondary line the three sections were:

(1) A front of five miles from the Tagus at Alhandra along the crest of a steep but not very lofty ridge, as far as the great ravine that overlooks the village of Arruda. This front was elaborately fortified, as it blocks the great road, in the flat by the waterside, which forms the easiest approach to Lisbon from the north. In the five miles there were ultimately constructed no less than 23 redoubts with 96 guns. Two thousand yards of hillside in one place had been scarped into a precipice; a mile by the side of the Tagus had been inundated. The one considerable gap in the line, the ravine at the head of the valley of Calandriz, had been choked by one of the great abattis above described. The redoubts required a garrison of 6,000 men.

(2) The second section, from the ravine above Arruda to the left of the steep Monte Agraça, formed somewhat of a salient angle: it had a front in all of some four and a half miles, which included the most lofty and defensible part of the backbone range of the Lisbon peninsula. One of the four great paved roads entering the capital from the north, however, passes over the shoulder of these heights, and they were therefore very heavily fortified from the first, the large redoubt for 1,600 men, on the top of Monte Agraça being one of the original outer works ordered for construction in Wellington’s earliest notes of October 1809. There were in all seven redoubts mounting 55 guns and requiring a garrison of 3,000 men on this fraction of the lines.

(3) Quite different in character was the front of eight miles from the left of Monte Agraça to the pass of Runa, overlooking the upper valley of the Zizandre and the village of Sobral. The fortification of this line had not entered into Wellington’s original plan, and there were only two redoubts upon it when Masséna appeared before it in October 1810. Such defence as there was consisted in the fact that the dominating Monte Agraça redoubts overlooked it on the right, and that the two small works just mentioned commanded the main high-road from Sobral to Cabeça de Montechique, which goes through its centre. But there was a clear possibility that the enemy might make a push up the valley and the high-road, by the village of Zibreira, and this was indeed the most probable point of attack in the whole 29 miles of front for the enemy to select. When, at the last moment, the British Commander-in-Chief determined to hold the outer lines, and not merely to fall back after having used them for a temporary defence, he had to cram this point with troops, and to construct new works upon it as quickly as possible. Four divisions, therefore, more than 20,000 men, were concentrated here. Wellington’s own head quarters were established at the hamlet of Pero Negro, on the slope above the high-road, and a very large redoubt was thrown up on the Portello hill, above Zibreira, with several smaller ones further to the right, to connect it with the Monte Agraça works. Sobral, the village at the foot of the heights, was held as an outpost, but abandoned when Masséna pushed forward to the front, as it was too far advanced to the north to be treated as an integral part of the position. But the French, when they had carried Sobral with difficulty, looked at the main line behind it, and refused to attempt any further advance. The hillside was as formidable as the Bussaco heights from which they had only recently been repulsed: it was full of troops and growing in strength every moment as the earthworks continued to arise.

(4) The fourth section of the outer or northern front was that from the gorge of the Zizandre (or the pass of Runa, as it is sometimes called) to the sea. It was about twelve miles long, but of this space six miles and more was covered by the impassable bog formed by the obstructed Zizandre, and another mile was formed by the formidable entrenched camp of San Vincente, above the town of Torres Vedras, the most complete and self-sufficing of all the works in the peninsula. This stronghold lay outside the main line, beyond the river, covering the bridge and the paved chaussée from Leiria to Lisbon, the only carriage-road on the western side of the Lines[486]. It was one of the earliest of the fortifications commenced by Wellington’s engineers, having been started on November 8, 1809, and was placed in such a conspicuous point, and planned on such a large scale, that it attracted public attention more than any other part of the works, and gave its name to the whole in popular parlance[487]. The whole front on both sides of Torres Vedras and its great fort was so strong and inaccessible as to offer little temptation to the invader to select it as a point of serious attack, all the more so because troops brought opposite to it would be completely cut off from any left in front of the eastern and central part of the lines. For the geography of the peninsula at this point is peculiar: north of the gorge of the Zizandre the great backbone range, the Serra de Barregudo and the Serra de Monte Junta, extends for a distance of fifteen miles, without being crossed by a single road practicable for horses, much less for wheeled vehicles. There are nothing but goat-tracks across the heights. If, therefore, any considerable body of troops had been sent to observe or contain the western section of the lines, it would have been separated by two days’ march from the rest of the army, and liable to be crushed, ere succoured, by the defenders of Lisbon, who had good cross-roads across the peninsula, by which they could transfer themselves from point to point under the protection of their works. As a matter of fact, nothing but flying parties of French horse ever appeared in this direction. Masséna had not troops to spare for any secondary attack, more especially for one on such an unpromising part of the Lines. Wellington had foreseen this when he distributed his field army behind the various sections of the front: to support the garrisons of the twelve miles of redoubts about Torres Vedras he only placed one division, while there were three behind the eastern section, and more than four in the partially entrenched central part[488].

Passing on to the second line of defence, from Quintella on the Tagus to the mouth of the Rio São Lourenço on the Atlantic, we find three sections of defence, which, unlike those of the outer line, were all completed by September 1810, and had no central gap.

(1) There was over a mile of impassable inundation at the eastern end, between Quintella and Alverca. Above the first-named village was an isolated hill, which was all fortress, for no less than six redoubts had been placed upon it, to enfilade the high-road across the inundated lower ground. Then came the Serra de Serves, three miles of lofty and difficult hills, which had been scarped into almost perfect inaccessibility. In a sudden dip west of this range was the pass of Bucellas, through which runs one of the three great high-roads that enter Lisbon. It was easily defensible, as it lies between two high and steep mountain-sides, and is only a couple of hundred yards broad. Redoubts were placed so as to rake it from end to end, and to flank it on both sides. The chaussée itself was blocked with successive abattis, and the viaduct leading up to it was mined.

(2) The second section of the inner line extended from the pass of Bucellas to the Park of Mafra, a front of over six miles. The eastern part of this was formed by the towering heights of the Cabeça de Montechique, the most dominating mountain-summit in the whole peninsula, almost steep enough to defend itself without fortification; but three redoubts nevertheless had been reared upon its summit. But from the pass of Montechique, at the left side of the summit, down to Mafra the ground was less well marked, and here the chaussée from Sobral and Zibreira crossed the range. Much fortification, therefore, was lavished on these four miles, along which there were nine strong redoubts, connected with each other in the rear by a military road passing along the southern crest of the heights. There was a second and formidable ridge behind this line, where further defence could be offered in the unlikely event of the enemy forcing his way up the high-road.

(3) From Mafra to the sea, nearly ten miles, there was for the most part a well-marked line of heights protected in front by the ravine of the river of São Lourenço, a deep, rugged, and in many cases inaccessible cleft, only crossed by a single road, that from Torres Vedras to Mafra. Nevertheless, six redoubts were reared, to cover this, and the few other points where the ravine was passable. The eastern part of this section, that along the wall of the Royal Park (Tapada) of Mafra, was its weakest portion, and for two miles at this point the British engineers set all their ingenuity to work. The outlying heights called the Serra de Chypre, in front of the park, were covered by four redoubts, and turned into a first defence. The wall of the Tapada itself was loopholed and furnished with a banquette. The important road which passes its foot was obstructed with cuts, enfiladed by the artillery of several works, and stockaded at more than one point. There was another group of redoubts along the south end of the Torres Vedras road, at the village of Morugueira; and finally Mafra town, in the rear of all, was turned into a defensive post by means of trenches and barricades. Altogether, what was by nature the weakest point in the southern lines was made by art one of the strongest. This too, in spite of the fact that, being approachable only from Torres Vedras, it was on the whole not a probable front on which to expect an attack.