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Maritime Exploration

Maritime Exploration

Author: Sophia Tutorial

Identify motivations for maritime exploration in the 15th century.

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what's covered
In 1492, Christopher Columbus famously sailed across the Atlantic Ocean to reach a New World for Europeans to explore. But he did not do this in an isolated context. This tutorial discusses the beginnings of Europe’s Age of Exploration, taking a look at those explorers who came before Columbus, as well as the Spanish footholds in the Americas that Columbus helped to initiate.

Our discussion will break down like this:
  1. Reasons for Exploration
  2. Portuguese Exploration
  3. Spanish Exploration
  4. Columbus Probanza de Mérito

1. Reasons for Exploration

Christopher Columbus’s voyages into the Americas were not the first time that European explorers made contact with a land and peoples vastly different from their own. Norse explorers such as Leif Erikson, the son of Erik the Red who first settled Greenland, had reached and established a colony in northern Canada roughly 500 years prior to Christopher Columbus’s voyage. Norse Vikings founded a tiny colony in Vinland, where they exchanged goods and knowledge with the indigenous population. By 1450, however, this settlement had mostly disappeared.

term to know
The coastal region of North America explored and settled by Vikings.

In fact, by 1450, most Europeans looked eastward rather than westward. Many Europeans migrated east and contributed to complex trade networks and systems of travel, including the Silk Road. In addition, the Crusades, which were fought between the 11th and 13th centuries, brought more Europeans into the Middle East.

The Crusades had lasting positive and negative effects on Europe. On the negative side, the wide-scale persecution of Jews began. Christians classified Jews with the infidel Muslims, and labeled them “the killers of Christ.” In the coming centuries, kings either expelled Jews from their kingdoms or forced them to pay heavy tributes for the privilege of remaining. Muslim-Christian hatred also festered, and intolerance grew.

On the positive side, maritime trade expanded between East and West. As Crusaders newly experienced the feel of silk, the taste of spices, and the utility of porcelain, their desire for these products created new markets for merchants. In particular, the port city of Venice, Italy, prospered enormously from trade with Islamic merchants. Starting in the tenth century, merchants’ ships brought Europeans valuable goods. These ships traveled along the Silk Road between the port cities of western Europe and the East. From the days of the early adventurer Marco Polo, Venetian sailors had traveled to ports on the Black Sea, and established their own colonies along the Mediterranean Coast.

However, transporting goods along the Silk Road was costly, slow, and unprofitable. Muslim middlemen collected taxes as the goods changed hands. Robbers waited to ambush the treasure-laden caravans. A direct water route to the East, cutting out the land portion of the trip, had to be found. As well as seeking a water passage to the wealthy cities in the East, sailors wanted to find a route to the exotic and wealthy Spice Islands in modern-day Indonesia, whose location was kept secret by Muslim rulers. Thus, many European cities and merchants, including those in Genoa and Florence (longtime rivals of Venice), looked west.

2. Portuguese Exploration

Portugal’s Prince Henry the Navigator spearheaded his country’s exploration of Africa and the Atlantic in the 1400s. With his support, Portuguese mariners successfully navigated an eastward route to Africa, establishing a foothold there that became a foundation for their nation’s trade empire in the 15th and 16th centuries.

Portuguese sailors used triangular sails and built lighter vessels called caravels that could sail down the African coast. Using these technologies, Portuguese mariners built an Atlantic empire by colonizing the Canary, Cape Verde, and Azores Islands, as well as the island of Madeira.

term to know
The governing control one nation has over another people’s economy, labor, geography, politics, et cetera.

Merchants then used these Atlantic outposts as debarkation points for subsequent journeys. From these strategic points, Portugal spread its empire down the western coast of Africa to the Congo, along the western coast of India, and eventually to Brazil on the eastern coast of South America. It also established trading posts in China and Japan. While the Portuguese didn’t rule over an immense landmass, their strategic holdings of islands and coastal ports gave them almost unrivaled control of nautical trade routes and a global empire of trading posts during the 1400s.

3. Spanish Exploration

Meanwhile, just to the east of Portugal, the history of Spanish exploration begins with the history of Spain itself. During the 15th century, Spain hoped to gain an advantage over Portugal. The marriage of Ferdinand of Aragon and Isabella of Castile in 1469 unified Catholic Spain, and this union began the process of building a nation that could compete for worldwide power. Since the 700s, much of Spain had been under Islamic rule, and King Ferdinand II and Queen Isabella I, arch-defenders of the Catholic Church against Islam, were determined to defeat the Muslims in Granada, the last Islamic stronghold in Spain. In 1492, they completed the Reconquista: the centuries-long Christian conquest of the Iberian Peninsula. The Reconquista marked another step forward in the process of making Spain an imperial power, and Ferdinand and Isabella were now ready to look further afield.

Ferdinand and Isabella with Catholic imagery

Their goals were to expand Catholicism and gain a commercial advantage over Portugal. To those ends, Ferdinand and Isabella sponsored extensive Atlantic exploration. For example, Spain’s most famous explorer, Christopher Columbus, was actually from Genoa, Italy. Columbus believed that, using calculations based on other mariners’ journeys, he could chart a westward route to India. This route could then be used to expand European trade and spread Christianity. Starting in 1485, Columbus approached Genoese, Venetian, Portuguese, English, and Spanish monarchs, asking for ships and funding to explore this westward route.

All those he petitioned — including Ferdinand and Isabella at first — rebuffed him, as their nautical experts all concurred that Columbus’s estimates of the width of the Atlantic Ocean were far too low. However, after three years of entreaties, and — more importantly — after the completion of the Reconquista, Ferdinand and Isabella agreed to finance Columbus’s expedition in 1492. They supplied him with three ships: the Nina, the Pinta, and the Santa Maria. The Spanish monarchs knew that Portuguese mariners had reached the southern tip of Africa and sailed the Indian Ocean. They understood that the Portuguese would soon reach Asia, and in this competitive race to reach the Far East, the Spanish rulers decided to act.

Most educated individuals at the time knew the earth was round, so Columbus’s plan to reach the East by sailing west was plausible. While the calculations of the earth’s circumference made by the Greek geographer Eratosthenes in the second century BCE were known (and, as we now know, nearly accurate), most scholars did not believe these calculations were dependable. As a result, Columbus would have no way of knowing when he had traveled far enough around the earth to reach his goal — and in fact, Columbus greatly underestimated the earth’s circumference.

In addition to believing the earth to be much smaller than its actual size, Columbus did not know of the existence of the Americas. Thus, when he set sail from Spain in August of 1492, he fully expected to land somewhere in Asia. On October 12, 1492, however, he made landfall on an island in the Bahamas. He then sailed to an island he named Hispaniola (present-day Dominican Republic and Haiti).

term to know
The island in the Caribbean, present-day Haiti and Dominican Republic, where Columbus first landed and established a Spanish colony.

Believing he had landed in the East Indies, Columbus called the native Taínos he found there “Indios,” giving rise to the term “Indian” for any native people of the New World. Upon Columbus’s return to Spain, the Spanish crown bestowed on him the title of Admiral of the Ocean Sea, and named him governor and viceroy of the lands he had discovered. Prior to sailing west, Columbus — a devout Catholic — had agreed with Ferdinand and Isabella that part of the expected wealth from his voyage would be used to continue the fight against Islam.

This 16th-century map shows the island of Hispaniola (present-day Haiti and Dominican Republic).

think about it
Note the various fanciful elements, such as the large-scale ships and sea creatures, and consider what the creator of this map hoped to convey. In addition to navigation, what purpose would such a map have served?

4. Columbus's Probanza de Mérito

Columbus’s 1493 letter — or probanza de mérito (proof of merit) — describing his “discovery” of a New World did much to inspire excitement in Europe. Probanzas de méritos were reports and letters written by Spaniards in the New World to the Spanish crown. These letters were designed to win royal patronage.

Today, such documents highlight the difficult task of historical work. While the letters are primary sources, historians need to understand the context and the culture in which the conquistadors — as the Spanish adventurers came to be called — wrote them, in order to distinguish their bias and subjective nature. While the letters are filled with distortions and fabrications, probanzas de méritos are still useful in illustrating the expectation of wealth among the explorers as well as their view that native peoples would not pose a serious obstacle to colonization.

Painted depiction of Columbus landing in the New World by John Vanderlyn (1847)

think about it
How does the image display certain biases and assumptions associated with Columbus’s discovery?

In 1493, Columbus sent two copies of a probanza de mérito to the Spanish king and queen, and to their minister of finance, Luis de Santángel. Santángel had supported Columbus’s voyage, helping him to obtain funding from Ferdinand and Isabella. Copies of the letter were soon circulating all over Europe, spreading news of the wondrous new land that Columbus had “discovered.” Columbus would make three more voyages over the next decade, establishing Spain’s first settlement in the New World on the island of Hispaniola.

Many other Europeans, drawn by dreams of winning wealth by sailing west, followed in Columbus’s footsteps. Another Italian, Amerigo Vespucci, sailed under the Portuguese crown between 1499 and 1502, in order to explore the South American coastline. Unlike Columbus, he realized that the Americas were not part of Asia but lands unknown to Europeans. Vespucci’s widely published accounts of his voyages fueled speculation and intense interest in the New World among Europeans.

German mapmaker Martin Waldseemüller was among those who read Vespucci’s reports. Using the explorer’s first name as a label for the new landmass, Waldseemuller attached “America” to his map of the New World in 1507, and the name stuck.

Columbus’s 1492 landfall accelerated the rivalry between Spain and Portugal, and the two powers vied for domination through the acquisition of new lands. In the 1480s, Pope Sixtus IV granted Portugal the right to all land south of the Cape Verde islands. This grant led the Portuguese king to claim that the lands discovered by Columbus belonged to Portugal and not Spain. Seeking to ensure that Columbus’s finds would remain Spanish, Spain’s monarchs turned to the Spanish-born Pope Alexander VI, who issued two papal decrees in 1493 that gave legitimacy to Spain’s Atlantic claims at the expense of Portugal.

Hoping to salvage Portugal’s Atlantic holdings, King João II began negotiations with Spain. The resulting Treaty of Tordesillas in 1494 drew a north-to-south line through South America. Spain gained territory west of the line, while Portugal retained the lands east of the line, including the east coast of Brazil.

Image of Cantino World Map

This 1502 map, known as the Cantino World Map, depicts the cartographer’s interpretation of the world in light of recent discoveries. The map shows areas of Portuguese and Spanish exploration, the two nations’ claims under the Treaty of Tordesillas, and a variety of flora, fauna, figures, and structures. What does it reveal about the state of geographical knowledge, as well as European perceptions of the New World, at the beginning of the 16th century?

In this tutorial we discussed how Atlantic exploration by the Portuguese and the Spanish marked an expansion of traditional east/west trade routes that previously existed between European Christians, Muslims, and the Far East. For centuries, commerce between these groups and regions occurred on land. However, various factors contributed to accelerated European efforts to find a direct sea route to Asia. While the Portuguese focused their attention southward to Africa, Spain focused westward and, in the process, stumbled upon the discovery of a “New World.” The establishment of trading posts and permanent settlements along the coasts of Africa and the New World provided the foundation for Portuguese and Spanish empires in the Atlantic during the 15th and 16th centuries.

This tutorial curated and/or authored by Matthew Pearce, Ph.D

Source: Image of Ferd and ISa, Public Domain,, Image of Columbus Landing, Public Domain,, Derived from Some sections removed., Derived from Some sections removed.

Terms to Know

The governing control one nation has over another people’s economy, labor, geography, politics, etc.


The island in the Caribbean, present-day Haiti and Dominican Republic, where Columbus first landed and established a Spanish colony.


The coastal region of North America explored and settled by Vikings

People to Know
Amerigo Vespucci

Italian explorer who navigated the South American coastline between 1499 and 1502 for the Portuguese crown.

Christopher Columbus

Genoese explorer commissioned by the King Ferdinand and Queen Isabella of Spain to find a westward route to India. Columbus sailed to the island of Hispaniola in 1492, opening up the Americas to European exploration.

Ferdinand and Isabella

King and Queen of Spain who ruled during the Reconquista and promoted New World exploration, including the voyages of Christopher Columbus, in the late 15th and early 16th centuries.

Leif Erikson

Son of Erik the Red, the Norse explorer who established the first permanent settlement in Greenland. Erikson is believed to have visited North America 500 years before Christopher Columbus.

Prince Henry the Navigator

Portuguese prince who supported exploration of the African coast and the Atlantic Ocean in the 1400s.

Dates to Know

Islam spreads out from the Arabian peninsula, reaching Spain by the 700s.

1000 - 1100

Norse settlements are established in modern-day Canada.

1095 - 1291

The Crusades lead to cultural exchanges between Europe and civilizations to the east.

1400 - 1500

Portuguese sailors explore and colonize the west coast of Africa and various Atlantic islands.


Catholic Spain is unified with the marriage of King Ferdinand and Queen Isabella.


Spanish Reconquista expels remaining Muslims from the Iberian peninsula; Christopher Columbus, with funds from Spain, sails west and lands on Hispaniola.


The Treaty of Tordesillas divides the Americas between Spain and Portugal.

1499 - 1502

Amerigo Vespucci, funded by the Portuguese crown, explores the coast of South America.


Martin Waldseemüller makes a map using the name "America" for the first time.