[1] In 1807, during the Peninsular War (1807-14), France and Spain signed the secret Treaty of Fontainebleau foreseeing the invasion and subsequent division of Portuguese territory into three kingdoms.

Portugal called for support from England while, at the same time, the Portuguese royal family left the country for Brazil.

Wellington then decided to construct lines of defence for Lisbon, in order to defend against any further invasion and also to protect his own retreat and possible evacuation if overwhelmed by French forces.

A third French invasion, headed by Marshal André Masséna advanced to the Lines of Torres Vedras but could not pass them and after five months was forced to retreat.

Occupying a dominant position, the Fort of Feira was at the centre of a complex of 19 strongholds in the second Line of Torres Vedras.