The Peninsula on which Lisbon stands, is traversed by two lofty heights, which stretch from the Tagus to the ocean, varying in altitude and abruptness, and running in a parallel direction, at a distance of from six to nine miles. Through the passes in these mountains, the four great roads that communicate between Lisbon and the interior run. The line on the Sierra next the capital is the stronger of the two. It commences at Ribumar, on the Rio Lorenzo, runs by Mafra, Cabeca de Montachique, and the pass of Bucellas, and descends precipitously on the plain, about an English league from the Tagus. This latter is the only weak point--and every means that skill and labour could effect, was exhausted to fortify every spot that Nature had left open, and thus render Torres Vedras--its extent considered--the strongest position in Europe.[122] “In front of Via Longa, upon an eminence rising from the plain, at a short distance from the river, six redoubts were constructed, so situated, in consequence of the nearly circular formation of the plateau, as to command the approaches in every direction within the range of their artillery. Three of these immediately domineered the great route from Alhandra to Lisbon, to the right of which, upon a knoll, in front of the town of Povoa, another work was formed, sweeping the communication in the direction of Quintella. On the bank of the Tagus, a redoubt, armed with four twelve-pounders, terminated the line at its eastern extremity. Fifty-nine redoubts, containing two hundred and thirty-two pieces of cannon, estimated to require seventeen thousand five hundred men to garrison them, protected the weaker points, enfiladed the roads, or swept the ascent to the escarped mountains in the range of this extended position, occupying a front of twenty-two miles.” “The front line had been originally intended for one of isolated posts, rather than an unbroken extent of defensive ground, which it was subsequently made. It rests also on the Atlantic at the mouth of the Lozandra; its weakest point being in the rear of the village of Runa, where it stretches to Monte Agraça, and ample care was taken to correct this natural defect.” “On the Sierra, in the rear of Sobral, was constructed a redoubt of great magnitude, armed with twenty-five pieces of artillery, and prepared for a garrison of one thousand men. This formidable work, from its commanding and centrical situation, was the constant daily resort of Lord Wellington. There he came every morning, and continued until it was ascertained that no hostile movement had taken place, and until light permitted a _reconnaissance_ of the enemy’s troops encamped opposite. From the redoubt on Monte Agraça, the line continued, crossing the valleys of Arruda and Calhandriz, until it rested on the Tagus at Alhandra.”