Duarte Pacheco Pereira (; c. 1460 – 1533), called the Portuguese Achilles (Aquiles Lusitano) by the poet Camões, was a Portuguese sea captain, soldier, explorer and cartographer. He travelled particularly in the central Atlantic Ocean west of the Cape Verde islands, along the coast of West Africa and to India. His accomplishments in strategic warfare, exploration, mathematics and astronomy were of an exceptional level.
Background
Pacheco Pereira was the son of João Pacheco and Isabel Pereira. In his youth he served as the King of Portugal's personal squire. In the year of 1475, having graduated with honors, he was awarded a study fellowship from the monarch himself. Later on, in 1488 he explored the west coast of Africa. His expedition fell ill with fever and lost their ship. Pacheco Pereira was rescued from the island of Príncipe in the Gulf of Guinea by Bartolomeu Dias when Dias was returning from rounding the Cape of Good Hope for the first time.
The knowledge he collected from Dias expedition as well as his own explorations granted him the post of official geographer of the Portuguese monarch. In 1494 he signed the Pope-sanctioned Treaty of Tordesillas, which shared the non-Christian world between Portugal and Spain.
Pacheco in India
In 1503 Duarte Pacheco Pereira departed for India as captain of Espírito Santo, one of the three ships in the fleet headed by Afonso de Albuquerque. In 1504, he was placed in charge of the defence of Cochin, a Portuguese protectorate in India, from a series of attacks between March and July 1504 by the ruling Zamorin of Calicut. (see Battle of Cochin (1504)). Having only 150 Portuguese and a small number of Malabarese auxiliaries at his disposal, Cochin was vastly outnumbered by the Zamorin's army of 60,000. Nonetheless, by clever positioning, individual heroics and a lot of luck, Duarte Pacheco successfully resisted attacks for five months, until the humiliated Zamorin finally called off his forces. His son Lisuarte (or Jusarte) took a leading part in the fight.
For his exploits in the defense of Cochin, Duarte Pacheco was given a grant of arms by the Trimumpara Raja of Cochin, and greeted with honors by King Manuel I of Portugal and public festivities upon his return to Lisbon in 1505.
After India
His diary (1506), preserved in the Portuguese National Archive (Torre do Tombo), is probably the first European document to acknowledge that chimpanzees built their own rudimentary tools.
Between 1505 and 1508 Duarte Pacheco Pereira composed a book, Esmeraldo de situ orbis, inspired on Pomponius Mela's De situ Orbis, which has been described as one of the first major scientific works "reporting on what was observed and experimented in the newly 'discovered' environment." Never completed, it was not published until 1892, possibly to avoid giving others information about Portugal's valuable Guinea trade.
(The meaning of the 'esmeraldo' in the title has been much speculated. Among the proposals, it is a reference to the emerald green of the sea; that it is an anagram combining the names 'Emmanuel' (for King Manuel I of Portugal) and 'Eduardus' (of Duarte Pacheco), that Esmeralda might have been the name (or nickname) of the ship Duarte Pacheco sailed to India, that it is a corruption of the Spanish word esmerado (meaning "guide"), that in Malayalam, an emerald gemstone is known as pache or pachec, and thus Esmeraldo is a pun on his own name (thus, "Pacheco's De Situ Orbis").
Duarte Pacheco Pereira was probably one of the first early modern Europeans to scientifically study the relationship between the tides and the phases of the moon, which played a critical importance in the course of the Battle of Cochin, and carefully took notes on the timing of the tides. Pacheco is said to have been the first to notice their connection to the moon and to establish rules for predicting the progress of tides by reference to lunar observations. He also sifted through his data to correct and improve astronomical observations (notably correcting the average daily deviation of the moon from the sun) and constructing nautical measurements to be used by future Portuguese navigators.
In 1508, Duarte Pacheco was commissioned by the Portuguese king to give chase to Mondragon French privateer which operated between the Azores and the Portuguese coast, where they attacked the ships coming from Portuguese India. Duarte Pacheco located and cornered Mondragon off Cape Finisterre in 1509, and defeated and captured him.