Beyond his poems, Arriaza wrote several political pamphlets. The first was published at Seville in 1809, after the battle of Talavera, when the English, notwithstanding the victory, had to retreat into Portugal, giving occasion to the French party in Spain to allege that they were about to abandon the country to the French, and keep possession of the principal ports. In this pamphlet, which he entitled the ‘Pharos of Public Opinion,’ Arriaza combated these suspicions, and by a strenuous assertion of the good faith of the English, succeeded in disabusing the minds of his countrymen of what he termed “such malignant insinuations.” The second pamphlet he termed ‘Virtue of Necessity,’ shortly after the disastrous battle of Ocania; and its object was to stimulate the English government and nation to give more assistance than they had yet done, by money and otherwise. He proposed in return to give the English free right of commerce with the Spanish colonies in America, at least for a stated period, observing that they already had extensive dealings with them by contraband, and that the free commerce would make the English neutral, at least, in the question of the colonies wishing to declare themselves independent, while otherwise it would be their interest to have them independent. This pamphlet especially is full of sound statesmanlike ideas, and proves how well he was acquainted with the state of public feeling in England, on the several particulars respecting which he was writing. A third pamphlet he wrote in English, and published it in London in 1810, where he was then sent on the part of the Spanish government. This he entitled ‘Observations on the system of war of the Allies in the Peninsula;’ and he endeavoured in it to urge the English to send more troops to the Peninsula, at certain points, where he considered they would be of most avail in disconcerting the plans of the French, and assisting the Guerrilla warfare the Spaniards were carrying on. He explained the determined fidelity of the Spaniards to the cause of their independence, but showed they would be insufficient to effect it, without the assistance he came to seek. This pamphlet was favourably received in England, and was noticed in Parliament; and the author had the good fortune to hope that his efforts had been successful, as he says, “The English government then sent greater reinforcements to their army, which emerging from its inaction, acquired the superiority preserved until the happy conclusion of the war.”