Part of my undergraduate thesis in Classical Languages and Literature is a translation of a Portuguese historian’s work on the explorations, written in 1540.

Excerpt from my translation into English:

—
In the fourteen hundred and thirty-third year from the birth of the Savior of the human race, Christ, King John of Portugal died, surnamed the Great, the first of that name, who freed Portugal from the incursions of the Castilians and their attacks, which almost devasted the whole country.

Among those sons who remained, Henry was of all the rest most learned, expecially in astronomy; Henry lived a celibate life because of his study of the stars, and so that he might more carefully concentrate on the source of the stars, spent his life on that sacred point, which is called Cape St. Vincent.

He chose this place because rarely is the sky disturbed there, so the clouds would not obstruct the instruments, which he used for the calculations in his work, and so he would not be impeded from his contemplation of the course of the heavens.

This Henry, however, to gather the fruit of his labor, which he had already discovered from many vigils, that surely the Atlantic Ocean flowed into the Indian Ocean, and the Indian Ocean again flowed into the Atlantic, decided to investigate his assumptions with his own ships and at his own expense.

These ships, having been sent on repeated expeditions, penetrated a good part of the Atlantic coast, and cities and states, and a great many islands were found. In all these places the Faith of Christ was made known through his work, and also in these places churches were built, especially in the islands formerly uninhabited.
— end excerpt —

Entire LORAS COLLEGE THESIS:
http://community.webtv.net/HeavyAttackGuestBook/LorasCollegeThesis/

The militant battless between Christians and Muslims in that time are eerily predictive of our modern century.