resulting from independence movements in South America. For instance, Jerónimo Valdés participated in the battle of Ayacucho (1824). Both sides executed prisoners of war by firing squad; the most notorious incident occurred at Heredia, when 118 Liberal prisoners were executed by order of Zumalacárregui. The British attempted to intervene, and through Lord Eliot, the Lord Eliot Convention was signed on April 27–28, 1835. The treatment of prisoners of the First Carlist War became regulated and had positive effects. A soldier of the British Auxiliary Legion wrote: The British and Chapelgorris who fell into their hands [the Carlists], were mercilessly put to death, sometimes by means of tortures worthy of the North American Indians; but the Spanish troops of the line were saved by virtue, I believe, of the Eliot treaty, and after being kept for some time in prison, where they were treated with sufficient harshness, were frequently exchanged for an equal number of prisoners made by the Christinos. However, Henry Bill, another contemporary, wrote that, although "it was mutually agreed upon to treat the prisoners taken on either side according to the ordinary rules of war, a few months only elapsed before similar barbarities were practiced with all their former remorselessness." War Northern front The war was long and hard, and the Carlist forces (labeled "the Basque army" by John F. Bacon) achieved important victories in the north under the direction of the brilliant general Tomás de Zumalacárregui. The Basque commander swore an oath to uphold home rule in Navarre (fueros), subsequently being proclaimed commander in chief of Navarre. The Basque regional governments of Biscay, Álava, and Gipuzkoa followed suit by pledging obedience to Zumalacárregui. He took to the bush in the Amescoas (to become the Carlist headquarters, next to Estella-Lizarra), there making himself strong and avoiding the harassment of the Spanish forces loyal to Maria Christina (Isabella II). 3,000 volunteers with no resources came to swell his forces. In summer 1834, Liberal (Isabeline) forces set fire to the Sanctuary of Arantzazu and a convent of Bera, while Zumalacárregui showed his toughest side when he had volunteers refusing to advance over Etxarri-Aranatz executed. The Carlist cavalry engaged and defeated in Viana an army sent from Madrid (14 September 1834), while Zumalacárregui's forces descended from the Basque Mountains over the Álavan Plains (Vitoria), and prevailed over general Manuel O'Doyle. The veteran general Espoz y Mina, a Liberal Navarrese commander, attempted