The combat of Lequeitio (21-22 June 1812) was the first of a series of successes for a joint British and Spanish force operating in northern Spain.
During 1812 the Royal Navy posted a squadron under Captain Home Popham off the north coast of Spain, with orders to co-operate with the Spanish. The idea had come from Popham, but Wellington approved of it, hoping that it would prevent General Caffarelli's Army of the North sending reinforcements to Marmont's Army of Portugual, which was his main target during the Salamanca campaign. Popham had the support of General Castanos, the captain-general of Galicia, and was often able to rely on the support of the local guerrilla bands. Popham began the campaign with the ships of the line HMS Venerable and HMS Magnificent (later replaced by the Abercrombie) and the frigates Medusa, Isis, Diadem, Surveillante and Rhin and two battalions of marines, and also carried stocks of arms for the Spanish guerrillas.
Popham's first target was the port of Lequeitio. This was defended by a fort and a fortified convent, with a garrison made up of at least 290 men from the 119th line, under chef de bataillon Gillort. The fort was impossible to bombard from the sea, and so a party under Captain the Hon. Duncombe Pleydell Bouverie landed a 24-pounder and dragged it onto a nearby hill. By the end of 21 June the single gun had created a breach, and the Spanish guerrillas of 'El Pastor' (Don Gaspar de Jauregui) attacked and captured the fort.
During the following night a party of British sailors captured the nearby island of San Nicolas. The 24-pounder was then used to threaten the convent, where Gillort quickly surrendered. Lequeitio remained in Allied hands for some time. In August it was used as a base for the successful attack on Bilbao (13-14 August)
After the fall of Lequeitio Popham moved west, destroyed abandoned forts at Bermeo and Plencia. An attempt to capture Guetaria, which would have threatened the main road back to France, had to be abandoned, and his next success came at Castro Urdiales (6-8 July 1812).