Sir Charles Oman's History of the Peninsular War Volume III

Ocaa, Cadiz, Bussaco, Torres Vedras

Volume III covers the period from September 1809 to December 1810, when the French were consolidating their hold on Spain, crushing resistance and attempting to drive the British out of Portugal. However, they could not wholly defeat their opponents. The forces of the Spanish Regency Council, with British and Portuguese aid, held out against the siege of Cadiz. Wellington's Allied army fought a model defensive battle at Bussaco, stalling the French drive into Portugal and enabling the British and Portuguese forces to retire to the shelter of the Torres Vedras fortifications. Here the Allies' defence led to a strategic victory, blunting the French offensive, and ultimately forcing the French to abandon their invasion of Portugal.