Andrés de Pez, son of Capt. Andrés de Pez y Capetillo and María de Malzárraga, was born in Cádiz, Spain, and christened in the cathedral there on July 10, 1657. At the age of sixteen he entered the naval guard as an ordinary soldier. In the battle of Palermo, on June 2, 1676, he saw his brother and his father, both naval captains, slain by the French, for whom he thereafter held a lifelong enmity. In his early career Pez served on escort vessels to and from the Americas and acquired the skills of draftsman, cartographer, and cosmographer. Rising through the ranks, he became a company commander in the Armada de Barlovento, the "Windward Fleet" charged with guarding Spanish ships and colonies in the Caribbean Sea and Gulf of Mexico. He won a reputation for "outstanding bravery and efficiency" in combatting French pirates. In June 1686 he became captain of the presidio at Veracruz.
Because of his enmity for the French, Pez fitted naturally into a leading role in the Spanish search for La Salle's colony on the Texas coast. His initial participation in the search was as captain of the frigate Santo Cristo de San Román and second in command to Francisco López de Gamarra on the third maritime expedition, sent in search of the overdue ships of captains Martín de Rivas and Pedro de Iriarte. On the basis of the diary by Pez's pilot, Luis Gómez Raposo, this voyage has been touted as the most significant of the multipronged search effort. Actually, it pales beside the Rivas-Iriarte voyage, as shown by the diary of Juan Enríquez Barroto. Pez, in later years, claimed for himself discoveries actually made on the previous voyage. With smaller ships, Rivas and Iriarte were able to probe shallow bays and inlets that were inaccessible to López de Gamarra and Pez's deep-draft frigates and to explore more closely the mouths of the Mississippi River.
In March 1688 Pez, with Enríquez Barroto as his second in command, explored the coast from Mobile Bay to the Mississippi's North Pass in response to the spurious tale of an English pirate who claimed to have visited the French colony. In August 1688 Pez sailed as second in command to Captain Rivas on yet another quest for the French settlement. With the two small ships (called piraguas) of the Rivas-Iriarte expedition, the expedition explored "twenty leagues" of the Soto la Marina River of Tamaulipas. With "canoes," they examined the Rio Grande upstream, possibly as far as the site of present Roma. This was the first known instance of European craft on the international stream. On the basis of Enríquez Barroto's 1686 rediscovery of Pensacola Bay, Pez became the champion of that location for Spanish occupation. After Alonso De León had found La Salle's Fort St. Louis in April 1689, Pez voyaged to Spain to lay before the crown the so-called "Pez Memorial," actually drawn up by the Mexican savant Carlos de Sigüenza y Góngora from data provided by Enríquez Barroto. Pez took to Spain two members of the La Salle expedition, Jacques Grollet and Jean L'Archevêque, whom De León had found in the Texas wilderness. While in Spain Pez was knighted by the Order of Santiago and won reluctant crown approval for a new coastal exploration preliminary to eventual occupation of the Pensacola site.
When he returned to New Spain, he was elevated to general (commander in chief) of the Armada de Barlovento. The viceroy, Conde de Galve, nevertheless directed him to carry out the exploration of Pensacola Bay and environs and gave him Sigüenza for mapping and scientific observation. Actual settlement at the bay, however, was delayed several years, and Pez-even after a second voyage to Spain to promote it-was denied a part. As the result of the loss of the Armada de Barlovento's almiranta (admiral's flagship) to the French, he had come under charges of cowardice and neglect of duty. The allegations stemmed from the capture on January 7, 1697, between Cuba and Hispaniola, of the forty-six-gun Santo Cristo de Maracaibo, commanded by Adm. Guillermo Morfi.
Eventually exonerated, Pez suffered little damage to his career. During the War of the Spanish Succession, he fought the Catalán rebels who refused to accept the Bourbon prince Philip V (grandson of the French king Louis XIV) as their monarch, and served as captain-general of the Indies fleet from 1708 to 1710. Pez was received in 1715 as a member of Spain's Supreme War Council. In 1717 he was named governor of the Council of the Indies. He was named secretary of state and navy in 1721. The Bourbon Family Compact having ended with the death of Louis XIV and the French seeking to extend their Louisiana colony into Texas, Pez proposed action to curb French aggression. Among other recommendations, he urged in March 1718 that the East Texas missions and those soon to be established at San Antonio be maintained at all costs, that a fort should be established at Matagorda Bay, and that the French should not be allowed to purchase horses in Spanish territory, i.e., Texas. On May 20, 1718, the Council of the Indies endorsed Pez's suggestions, thus setting the tone of future Franco-Spanish rivalry in the Gulf region. Pez died in Madrid in 1723, the day variously given as March 9 and May 7.