The siege of Cádiz was a siege of the large Spanish naval base of Cádiz by a French army from 5 February 1810 to 24 August 1812 during the Peninsular War. Following the occupation of Seville, Cádiz became the Spanish seat of power, and was targeted by 70,000 French troops under the command of the Marshals Claude Victor and Nicolas Jean-de-Dieu Soult for one of the most important sieges of the war. Defending the city were 2,000 Spanish troops who, as the siege progressed, received aid from 10,000 Spanish reinforcements as well as British and Portuguese troops.

The Peninsular War (1807–1814) was the military conflict fought in the Iberian Peninsula by Spain, Portugal, and the United Kingdom against the invading and occupying forces of the First French Empire during the Napoleonic Wars. In Spain, it is considered to overlap with the Spanish War of Independence.