After a French relief attempt failed, Brenier and his troops broke out at night after blowing up portions of the fortress.

On 11 October 1810, Marshal André Masséna's French army found itself confronted by the elaborately built and well-defended Lines of Torres Vedras in its invasion of Portugal.

[1] The British army of Viscount Wellington beat the French II Corps of General of Division Jean Reynier at the Battle of Sabugal on 3 April 1811.

[3] After Marshal André Masséna's retreat from Portugal, the French installed a garrison of 1,400 men under Brenier in the fortress.

Though instructed by Wellington to block the Barba del Puerco bridge on the afternoon of the 10th, Erskine neglected to forward the necessary orders in time.

Campbell and Brigadier General Denis Pack gave chase with some troops, but a British colonel whose regiment was stationed near the breakthrough failed to pursue.

[4] The failed blockade occurred at the end of the third Portuguese campaign, which had begun the following year with the French capture of Almeida.