Lesson
Prince Henry the Navigator Sponsors Systematic Coastal Surveying
Bridge-in
Maps have long shaped how societies claim and control territory, from ancient portolan charts to modern satellite imagery. In the early 15th century, European powers began using maritime exploration not just to discover new lands but to assert legal and commercial claims over coastal regions. Prince Henry of Portugal turned this practice into a state-sponsored project, laying the groundwork for Portugal's dominance in Atlantic trade networks.
Objective
By the end of this lesson, you will be able to describe how Prince Henry of Portugal organized systematic expeditions to map the West African coastline and establish early Portuguese claims to coastal trading access.
Pre-check — warm-up, not graded
What technological or navigational advancement allowed European sailors to sail farther along coastlines without relying on sight of land?
The development of the caravel, a maneuverable ship suited for coastal exploration, along with improved navigational tools like the compass and astrolabe, enabled longer coastal voyages.
Content
Beginning in 1419, Prince Henry of Portugal launched a sustained program of maritime expeditions along the West African coast. These voyages were not random acts of exploration but part of a coordinated effort to chart unknown shores, claim territory for the Portuguese crown, and secure access to lucrative trans-Saharan and coastal trade networks. Henry established a center for navigation and mapmaking at Sagres, where he gathered scholars, cartographers, and experienced sailors to plan and support each expedition. The first major milestone came in 1434 when Gil Eanes rounded the Cape Bojador, a psychological and geographical barrier that had previously discouraged sailors from venturing too far south. After this breakthrough, successive expeditions pushed progressively farther south, mapping islands such as Madeira and the Azores, and reaching the mouth of the Senegal River by the 1440s. Each voyage produced detailed coastal charts and reported on local populations, resources, and potential trading opportunities. These systematic surveys formed the basis of Portugal’s early claim to coastal trading access in West Africa, setting the stage for later fortifications and trade relationships. Henry’s sponsorship thus transformed coastal exploration into a tool of imperial policy, linking geographic knowledge directly to commercial and political ambition.
Post-check — self-check
Which geographic barrier did Gil Eanes famously round in 1434, enabling further Portuguese exploration along the West African coast?
Gil Eanes rounded the Cape Bojador in 1434.
Summary
From 1419 onward, Prince Henry of Portugal sponsored a series of organized expeditions that systematically mapped the West African coastline. These surveys, supported by a network of scholars and navigators at Sagres, enabled Portugal to assert early claims to coastal trading access and laid the foundation for future imperial expansion.
Check your understanding
What was the primary purpose of the expeditions sponsored by Prince Henry of Portugal beginning in 1419?
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