Prince Henry the Navigator

The intellectual architect of Portuguese exploration and the man most responsible for starting the Age of Discovery was Prince Henry the Navigator, who was motivated by religious zeal to send expeditions down the Atlantic coast of Africa, initially hoping to check Muslim power on the continent and make contact with Prester John, a legendary Christian king in Africa (the legend was probably a garbled version of the Christian kingdom of Ethiopia).  In the decades prior to Columbus’s arrival in Lisbon, Portuguese expeditions had pushed farther and farther southward down the West African coast, opening up new trade in gold, ivory, and African slaves along the way.  By the 1450s, the goal of circumnavigating Africa to reach Asia had been conceived.  
C. Raymond Beazley discusses the life and adventures of the famous explorer in this full length biography