[1] The threat of invasion of Portugal by the French during the Peninsular War (1807–14) led to the construction of the Lines of Torres Vedras in late 1809 and 1810, in order to protect Lisbon from Napoléon Bonaparte's troops.

Consisting of 152 forts and redoubts forming three lines of defence, the construction was ordered by the British commander, the Duke of Wellington, after two French invasions had already been repelled.

[2] Situated on the Ribas escarpment on a basalt hill, the Mosqueiro fort was built at an altitude of 332 metres and was designed for a garrison of 270 soldiers in order to control access along the Montachique, Ribas and São Gião gorges.

The fort included a magazine, gun emplacements, and an inner square for assembling troops, and was protected by palisades and a dry moat.

[2][3] In March 2012, the Municipality of Loures inaugurated a Centre of Interpretation of the Lines of Torres.