Lines of Torres Vedras

The Lines of Torres Vedras were lines of forts built in secrecy to defend Lisbon during the Peninsular War. Named after the nearby town of Torres Vedras, they were ordered by Arthur Wellesley, Viscount Wellington, constructed by Sir Richard Fletcher, 1st Baronet and his Portuguese workers between November 1809 and September 1810, and used to stop Masséna's 1810 offensive.

Genesis
After his troubling Spanish experience at the Battle of Talavera, Wellington decided to strengthen Portugal. He used a report of Colonel Vincent, ordered by Junot in 1807, describing the excellent defensive capacities in the region nearby Lisbon. It has been suggested that the study by Major Neves Costa influenced Wellington's decision to construct the lines, but in fact the plans pre-date Costa's study. He was also inspired by the Martello Towers along the English Channel coast. Wellington, after surveying the area personally, ordered in his detailed memorandum dated 20 October 1809 the building of the Lines of Torres as a system of fortifications blockhouses, redoubts, ravelins, cuts of natural relief, etc. The work began in the autumn of 1809 and the first line was finished one year later. Construction of the lines continued and in 1812 34,000 men were still working on them.

The work was supervised by Lieutenant-Colonel Sir Richard Fletcher, assisted by Major John Jones, 11 British officers, four Portuguese Army engineers and two KGL officers. The cost was around £100,000, one of the least expensive but most remunerative military investments in history.

Effects
The Anglo-Portuguese Army was forced to retreat to the lines after the Battle of Buçaco (27 September 1810). The French army under Marshal André Masséna discovered a barren land (under the scorched earth policy) and an enemy behind an impenetrable defensive position. Masséna's forces arrived at the lines on 11 October and took Sobral de Monte Agraço the following day. After driving in the Anglo-Portuguese skirmish line on 13 October, the VIII Corps tried to push forward on the 14th. In the Battle of Sobral they were repulsed in an attempt to assault a strong British outpost.

After attempting to wait out the enemy, Masséna was forced to order a French retreat to Spain, starting on the night of 15 November 1810, to re-supply and reinforce his army. Marshal Masséna began his campaign with his army (l'Armée de Portugal) at 65,000 strong. By the time he reached Torres Vedras, he had 61,000 men (after losing 4,000 at the Battle of Buçaco). When he reached Spain, he had lost 25,000 men (including those lost at Buçaco). One of the coldest winters the area had ever seen hit Portugal and killed many of the French forces. They were also hit by severe illness and disease killing the soldiers in the thousands. The human cost was great for the local population, because of the privations they endured. It is estimated that between October 1810 and March 1811 about 50,000 Portuguese died of hunger or disease.

The Allies were reinforced by fresh British troops in 1811 and renewed their offensive. They left the lines and did not return for the rest of the Peninsular War.

Description
The three lines of Torres Vedras had redoubts and forts strategically placed in the top of hills, controlling the roads to Lisbon and using the natural obstacles of the land. They did not comprise solid lines, instead they formed groupings of heavily defended areas that were self-supporting, with mobile troops based in fortified camps ready to counterattack when necessary.

The first line, with an extension of 46 km, binds Alhandra to the estuary of the Sizandro river. The second line, 13 km to the south, has 39 km and binds the Póvoa de Santa Iria to Ribamar. The third line consisted of a defensive perimeter with 3 km, from Paço de Arcos to the Tower of Junqueira, protecting a beach of embarcation (St. Julian's) about 27 km to the south of the second line, to be protected by British marines.

Initially using the Lisbon Militia units plus 5,000 to 7,000 hired peasants and later by conscription of all people within 40 miles, supervised by 18 engineering officers and around 150 NCOs and at a cost of just £100,000 the work was completed, just in time.

Within a year, by the time the French arrived 126 forts and redoubts were built, with ravelins, detached batteries, etc. Rivers were dammed, turning large areas into swamps, ravines were choked with abatis, miles of walls were built, some 16 ft high. Lateral roads were constructed to enable swift movement of supporting troops, houses and walls demolished to clear fields of fire, hills were scarped to make an unclimbable precipice, and everything was organised to have channels where cross fire from artillery would decimate an attacking force.

The three lines were furnished with 247 pieces of artillery and provided with around 30,000 men, mainly Portuguese militia and home guard ordenanças, plus 8,000 Spanish troops and 2,500 British marines and artillerymen. This left the Regular army, of around 58,000 (being 24,000 Portuguese and 34,000 British), able to manoeuvre behind the first line, to points of danger depending on where the invaders attacked the lines.

The majority of the defences were redoubts holding 200 to 300 troops and 3 to 6 cannon, normally 12 pounders which could fire canister shot or round shot. The redoubt was protected by a ditch, normally 16 ft wide and 12 ft deep, with parapets 8 to 14 ft thick fitted with fire steps and the redoubts were pallisaded.

A possible eastern approach down the Tagus was protected with anchored gun boats.

The fourth line was built south of the Tagus in the Almada highs to hinder an eventual invasion coming from south, with an extension of 8,000 yards (7.3 km): It had 17 redoubts and covered trenches, 86 pieces of artillery, defended by marines, and orderlies of Lisbon, for a total of 7,500 men.

Work continued on the redoubts and 152 were eventually completed.

Substantial portions of the lines still survive today, albeit heavily decayed due to locals re-using 100,000 tons of stones, although there has been some recent renovation work undertaken using EC funding.

Efficiency and cohesion
The efficiency and cohesion of the lines was based on five points:

1) Redoubts of artillery with Portuguese artillerymen, commanded by Major-General José António Rosa, and situated to fire into preset zones, where the enemy attack was expected. Both lines extended more than 80 km. The first line had 534 artillery pieces.

2) Military roads to cover the rear of the lines and allowing an extraordinary mobility of forces. In September 1810, the field army had some 66,598 regular soldiers. Including the Ordenanças and Milicias, it had 77,690 men.

3) A semaphore system introduced by the British Navy which allowed a message to be sent around the lines in 7 minutes, or from the HQ to any point in 4 minutes. The signal system had five stations:
 * Redoubt n.30 close to the ocean (Ponte do Rol)...
 * Fort São Vicente
 * Monte do Socorro close to Pêro Negro, Wellington’s headquarters. The station was reconstructed in 2008.
 * Monte Agraço
 * Sobralinho, by the Tejo.

4) Secrecy. The building of the lines took, surprisingly, only 10 to 11 months. Lisbon became a peninsula defended by a most efficient system of blockhouses. Everything was preserved as a secret, whose maintenance is as surprising as the building of the lines. Only one report appeared in the London newspapers, a major source of information for Napoleon. It is said that when Masséna was first confronted by the Lines, he asked his staff why they had not known about them in advance. "Wellington has made them", replied someone. Masséna shouted, "To the Devil with you! Did Wellington make the mountains?" It is also said that not even the British government knew about the forts and was stunned when Wellington first said in despatches he had retreated to them.

5) The scorched earth policy. North of the lines everything that could supply the invading army was collected, hidden or burnt. A vast tract of land was deserted and perhaps 200,000 inhabitants of the neighbouring districts of the lines were relocated inside the lines. That the French were able to campaign in their vicinity at all was a remarkable feat, according to Wellington: It is certainly astonishing that the enemy have been able to remain in this country so long; and it is an extraordinary instance of what a French army can do. ...They brought no provisions with them, and they have not received even a letter since they entered Portugal. With all our money, and having in our favour the good inclinations of the country, I assure you that I could not maintain one division in the district in which they have maintained not less than 60,000 men...for more than two months.