While thus employed in Italy as a statesman and a soldier, his active mind led him also to other pursuits. Many inedited philosophical works of his are to be found in Spanish libraries. He wrote a paraphrase of Aristotle, and a translation into Spanish of the Mechanics of that philosopher; he composed Political Commentaries, and a history of the taking of Tunis. In the library of manuscripts at Florence, Sedano tells us there exists a volume in quarto entitled, "Various Works of D. Diego de Mendoza, ambassador of his majesty to Venice, Turkey, and England." On all occasions he showed himself an enthusiastic lover of learning, and a liberal patron of learned men; as a proof of which the bookseller Paulus Manutius dedicated his edition of Cicero to him. Since the days of Petrarch, no man had been so eager to collect Greek manuscripts. He sent to Greece and Mount Athos to procure them, and even made their acquisition a clause in a political treaty with the Sultan. He thus collected a valuable library, which at his death he bequeathed to Philip II., and it forms a precious portion of the library of the Escurial.
It is, however, as a poet that his name is most distinguished in literature. He was a friend of Boscan, and entered into his views for enlarging the sphere of Spanish poetry by the introduction of the Italian style. Though a hitter enemy to the spirit of liberty in Italy, he could yet appreciate and profit by the highly advanced state of poetry and literature in that country, of which this very spirit was the parent.
It is mentioned in the record of his employments, that he went ambassador to England and Turkey; but it is uncertain at what time these journies were performed; probably before his return to Spain in 1554.
Considerable obscurity is thrown over the latter years of his life. That is, no sufficient pains has been taken to throw light upon them. His manuscript works would, doubtless, if consulted, tell us more about him than is at present known. He devoted a portion of the decline of his life to study and literature; but it would seem that on his return from Italy, he did not immediately retire from active life, as it is mentioned by some of his biographers that he continued member of the council of state under Philip II. and was present at the battle of St. Quentin, fought in 1557. One of the last adventures recorded of him is characteristic of the vehemence of his temper. While at court, he had a quarrel with a noble who was his rival in the affections of a lady. His antagonist, in a fit of exasperation, unsheathed a dagger; but before he could use it, Mendoza seized him and threw him from the balcony where they were standing, into the street below. In all countries in those days, a personal assault within the precincts of a royal court was looked upon as a very serious offence, and Spanish etiquette caused it to be regarded in a still more heinous light. Still Mendoza was not the aggressor: and his punishment was limited to a short imprisonment, where he amused himself by addressing the lady of his love in various redondillas.
Much of the latter part of his life was spent in retirement in his native city of Granada, given up to study and literature. He here composed the most esteemed of his prose works—the "History of the War of the Moriscos in Granada." The style of this work is exceedingly pure. He took the Latin authors Sallust and Cæsar for his models; and being an eye-witness of the events he records, his narrative is highly interesting.
While in Italy, he had written a state paper, addressed to the emperor, dissuading him from selling the duchy of Milan to the pope, which was conceived in so free a style, that Sandoval, in quoting it in his history, believed it necessary to soften its expressions. In the same way this acute observer perceived the faults of the Spanish government against the Moriscos, and alluded to, although he did not dare blame them.
Philip II., a bigoted tyrant, drove this portion of his subjects to despair. Mendoza tells us that just before their revolt, "the inquisition began to persecute them more than ever. The king ordered them to quit the Morisco language, and all commerce and communication one with the other: he took from them their negro slaves, whom they had brought up with the same kindness as if they had been their children: he forced them to cast off their Arab dress, in which they held invested a large capital, and obliged them, at a great expense, to adopt the Castilian costume. He forced the women to appear with uncovered faces, opening all that portion of their houses which they were accustomed to keep closed; and both of these orders appeared intolerable to this jealous people. It was spread abroad also that he intended to possess himself of their children, and to educate them in Castile: he forbade the use of baths, which contributed at once to their cleanliness and pleasure. Their music, songs, feasts, and weddings, held according to their manners and customs, and all assemblies of a joyful nature, were already interdicted; and these new regulations were published without augmenting the guards, without sending troops, without reinforcing the garrisons or establishing new ones."[22]
The effect of such a system on a proud and valorous people, passionately attached to their religion and customs, might be anticipated. The Moors collected arms secretly, and laid up stores in the rugged mountains of the Alpujarra: they chose for king the young Fernando de Valor, descended from their ancient sovereigns, who assumed the name of Aben Humeya. The progress of the revolt, however, met with various checks, and they did not receive the aid they expected from the sultan Selim. Instead, therefore, of taking Granada, their war became guerilla; and the spirit of vengeance incited them to the exercise of frightful cruelties, by way of reprisal, on the Christian prisoners who fell into their hands. An army was sent against them, commanded by don John of Austria, natural son of Charles V..; Mendoza's nephew, the marquis of Mondejar, was one of the principal generals under him: Mendoza, therefore, had full opportunity to learn the details of the war, which terminated in the success of the Spaniards, whose cruelties rivalled those of the unfortunate rebels. The Moriscos were put down by the massacre of several villages, and the selling of the inhabitants of a whole territory into slavery. This total destruction of the Morisco people is described by Mendoza, with a truth that prevented his history from being published until 1610, and even then with great omissions: a complete edition did not appear till 1776.
After a retreat of some years, Mendoza appeared at court again in his old age, at Valladolid: his reputation caused him to be admired as an oracle; his erudition and genius commanded universal respect. He enjoyed these honours but a few months, and died in the year 1575.
There are few men of whom the Spaniards are more proud than Mendoza, whom, to distinguish from other poets of the same name, they usually call the Ambassador. "Most certain it is," says Sedano, "that from the importance and diversity of his employments, he was considered one of the most famous among the many great men which that age produced. His ardent mind was perpetually employed in the support of the glory of his sovereign and the honour of his country; and in all the transactions in which he was employed, his zeal, his integrity, his deep policy, his penetration, and his understanding shone out; and the very faults of which he is accused, must be attributed to the envy and hatred of his enemies."