quality:corruption, structural:scholar_edition
1566 to 1580: Military service and captivity

In the 19th century, a biographer discovered an arrest warrant for a Miguel de Cervantes, dated 15 September 1569, who was charged with wounding Antonio de Sigura in a duel. Although disputed at the time, largely on the grounds such behaviour was unworthy of so great an author, it is now accepted as the most likely reason for Cervantes leaving Madrid.

He eventually made his way to Rome, where he found a position in the household of Giulio Acquaviva, an Italian bishop who spent 1568 to 1569 in Madrid, and was appointed Cardinal in 1570. When the 1570 to 1573 Ottoman–Venetian War began, Spain formed part of the Holy League, a coalition formed to support the Venetian Republic. Possibly seeing an opportunity to have his arrest warrant rescinded, Cervantes went to Naples, then part of the Crown of Aragon.

The military commander in Naples was Álvaro de Sande, a friend of the family, who gave Cervantes a commission in the Tercio of Sicily under the Marqués de Santa Cruz. At some point, he was joined in Naples by his younger brother Rodrigo. In September 1571, Cervantes sailed on board the Marquesa, part of the Holy League fleet under Don John of Austria, illegitimate half brother of Phillip II of Spain; on 7 October, they defeated the Ottoman fleet at the Battle of Lepanto.

This landmark sea battle, the most significant naval conflict since the Roman Battle of Actium (32 B.C.), stopped Muslim incursion into Europe, and for the first time allowed European Christians to feel that they were not to be overrun by Islam.

According to his own account, although suffering from malaria, Cervantes was given command of a 12-man skiff, a small boat used for assaulting enemy galleys. The Marquesa lost 40 dead, and 120 wounded, including Cervantes, who received three separate wounds, two in the chest, and another that rendered his left arm useless, this last wound is the reason why he later was called " El Manco de Lepanto " (English: "The one-handed man of Lepanto", "The one-armed man of Lepanto"), a title that followed him for the rest of his life. His actions at Lepanto were a source of pride to the end of his life, while Don John approved no less than four separate pay increases for him.

In Journey to Parnassus, published two years before his death in 1616, Cervantes claimed to have "lost the movement of the left hand for the glory of the right". As with much else, the extent of his disability is unclear, the only source being Cervantes himself, while commentators cite his habitual tendency to praise himself. However, they were serious enough to earn him six months in the Civic Hospital at Messina, Sicily.

Although he returned to service in July 1572 in the Tercio de Figueroa, records show his chest wounds were still not completely healed in February 1573. Based mainly in Naples, he joined expeditions to Corfu and Navarino, and took part in the 1573 occupation of Tunis and La Goulette, which were recaptured by the Ottomans in 1574. Despite Lepanto, the war overall was an Ottoman victory, and the loss of Tunis a military disaster for Spain. Cervantes returned to Palermo, where he was paid off by the Duke of Sessa, who gave him letters of commendation.

In early September 1575, Cervantes and Rodrigo left Naples on the galley Sol; as they approached Barcelona on 26 September, their ship was captured by Ottoman corsairs, and the brothers taken to Algiers, to be sold as slaves, or – as was the case of Cervantes and his brother – held for ransom, if this would be more lucrative than their sale as slaves. Rodrigo was ransomed in 1577, but his family could not afford the fee for Cervantes, who was forced to remain. Turkish historian Rasih Nuri İleri found evidence suggesting Cervantes worked on the construction of the Kılıç Ali Pasha Complex, which means he spent at least part of his captivity in Istanbul. This is yet to be proven and no evidence has been published on the matter.

By 1580, Spain was occupied with integrating Portugal, and suppressing the Dutch Revolt, while the Ottomans were at war with Persia; the two sides agreed a truce, leading to an improvement of relations. After almost five years, and four escape attempts, in 1580 Cervantes was set free by the Trinitarians, a religious charity that specialised in ransoming Christian captives, and returned to Madrid.