In the siege of Almeida, Portugal, the French corps of Marshal Michel Ney captured the border fortress from Brigadier General William Cox's Portuguese garrison.

The French received siege supplies from Ciudad Rodrigo on August 15, and started to dig trench lines to the south-east of the town, facing the San Pedro bastion.

When the French bombardment opened on August 26 at 6 AM, several quarters of the town were quickly set on fire, and the defending guns of the nearest three batteries overwhelmed.

At around 7 PM, one French shell landed in the courtyard, igniting a gunpowder trail that led through the still open door, and set off a chain reaction into the magazine.

The siege forms the climax of Bernard Cornwell's Sharpe's Gold, in which Richard Sharpe is credited with the destruction of the ammunition magazine, an act intended to deliberately cut short the siege so that he could leave the city and bring Lord Wellington the finances needed to complete the Lines of Torres Vedras.