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.

Nonetheless, by clever positioning, individual heroics and a lot of luck,[citation needed] Duarte Pacheco successfully resisted attacks for five months, until the humiliated Zamorin finally called off his forces.

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.

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.

Later in life, while away governing São Jorge da Mina, he was slandered by his enemies at court with accusations of theft and corruption.

[13] According to one of its most important biographers, the Portuguese historian Joaquim Barradas de Carvalho, who lived in exile in Brazil in the 1960s, Duarte Pacheco was a genius comparable to Leonardo da Vinci.

that Duarte Pacheco Pereira may have discovered the coasts of Maranhão, Pará and Marajó island and the mouth of the Amazon River in 1498, preceding the possible landings of the expeditions of Amerigo Vespucci in 1499, of Vicente Yáñez Pinzon in January 1500, and of Diego de Lepe in February 1500; and the Cabral's expedition in April 1500, making him the first known European explorer of present-day Brazil.

This claim is based on interpretations of the cipher manuscript Esmeraldo de Situ Orbis, written by Duarte Pacheco Pereira, which gives the following brief account: Most fortunate Prince, we have known and seen how in the third year of your reign in the year of Our Lord 1498, in which your Highness ordered us to discover the Western region, a very large landmass with many large islands adjacent, extending 70° North of the Equator, and located beyond the greatness of the Ocean, has been discovered and navigated; this distant land is densely populated and extends 28° degrees on the other side of the Equator towards the Antarctic Pole.

[16] The 1519 world map by Lopo Homem set out this concept, showing the OCEANUS MERIDIONALIS and INDICUM MARE (Atlantic and Indian Oceans) enclosed by the continental Earth.

In agreement with Luciano Pereira, such modern Portuguese historians as Faustino da Fonseca, Brito Rebelo, Lopes de Mendonça, and Jaime Cortesão say he did.

"[19]Duarte Pacheco Pereira's Esmeraldo de Situ Orbis is the first European navigation script book to mention the coast of Brazil.