Following the Treaty of Fontainebleau signed between France and Spain in October 1807, which provided for the invasion and subsequent division of Portuguese territory into three kingdoms, French troops under the command of General Junot entered Portugal, which requested support from the British.

In March 1809, Marshal Soult led a new French expedition that advanced south to the city of Porto before being repulsed by Portuguese-British troops and forced to withdraw.

Consisting of 152 forts and redoubts forming three lines of defence over 80 kilometres, making maximum use of the existing topography, the defensive lines were also designed to protect Wellington’s own retreat and possible evacuation from the Fort of São Julião da Barra on the Tagus estuary if overwhelmed by French forces.

[2] It was restored as part of the 200th anniversary celebrations of the Peninsular War and can be reached easily by car, along a dirt road.

In March 2012, the Municipality of Loures inaugurated a Centre of Interpretation of the Lines of Torres at Bucelas with the objective of making known to visitors the whole history of the fortifications built during the French invasions.