Spain's Real Gamble: Columbus & the Line of Demarcation

The Age of Exploration

Chapter 3 · Spain's Real Gamble: Columbus & the Line of Demarcation

Chapter 2 followed Portugal's route round Africa. This chapter follows Spain's different bet: sailing west across the Atlantic under Christopher Columbus, and the treaty that then divided the world between the two powers. The sources are two reference articles, one on Columbus's voyages and one on the Treaty of Tordesillas. They give the dates and the treaty's terms clearly, but say little about how Columbus obtained his backing or what he found, and the chapter marks that.

The Four Voyages

Columbus undertook four transatlantic expeditions between 1492 and 1504, sponsored by Spain's Catholic Monarchs.

VoyageWhat the source says
First, 1492 to 1493Departed 3 August 1492. Landfall on 12 October at an island Columbus named San Salvador (indigenous name Guanahani). Returned in March 1493.
Second, 1493 to 1496A larger fleet of 17 ships; explored the Lesser and Greater Antilles and established the La Isabela settlement.
Third, 1498 to 1500Columbus was arrested by the royal official Bobadilla and returned to Spain in chains.
Fourth, 1502 to 1504A final voyage exploring the coasts of Central America.
What Was Found Is Barely Described The source names the islands and settlements but does not describe the people who lived there, how the Spanish treated them, or why Columbus was arrested. I did not research the reasons, so the chapter does not describe conditions in the settlements. Chapter 9 covers the human cost of the period.

The Ships

The flagship Santa María was a carrack, while the Niña and Pinta were smaller caravels. The Santa María was wrecked on Christmas Day 1492 off Hispaniola, and its materials were used for Fort Navidad. Chapter 1 described the caravel as a fusion of Mediterranean and Northern European design, and Chapter 2 credited Prince Henry with promoting it, so two of Columbus's three ships were of the type Portugal had been using.

A Wrong Estimate

A Voyage Built on a Miscalculation Columbus miscalculated the Earth's size, believing it about 75 percent of its actual diameter. The source says he therefore estimated Asia to be only 2,400 nautical miles west of the Canaries, roughly one-fourth of the true distance, and quotes: "Columbus therefore estimated the size of the Earth to be about 75% of Eratosthenes's calculation." A shorter Atlantic made the plan look feasible.
Two Small Cautions The source does not say what Columbus's rivals or advisers thought of the estimate, so I cannot say whether it was an error at the time or only in hindsight. And the source's account implies, without stating it, that the Americas lay in the way; I did not find how Columbus interpreted what he found.

Who Saw Land First

Whether Columbus or the crew member Rodrigo de Triana first spotted land remains contested among historians. The source does not say what the evidence on each side is, so I do not choose.

The Treaty of Tordesillas, 1494

Signed on 7 June 1494 in Tordesillas, Spain, the treaty divided newly discovered lands outside Europe between Portugal and Castile along a meridian 370 leagues west of the Cape Verde islands.

Why It Was Needed

It resolved disputes after Columbus's return in 1493. Portuguese King John II claimed prior rights under the 1479 Treaty of Alcáçovas and the 1481 papal bull Aeterni regis, which granted him lands south of the Canary Islands.

The Allocation

"The lands to the east would belong to Portugal and the lands to the west to Castile," modifying Pope Alexander VI's earlier bulls. Portugal gained rights to Brazil's eastern quarter and eventually other African and Asian territories, while Spain received most of the Americas.

The Ambiguity

The treaty specified distance in undefined "leagues" from unspecified Cape Verde islands, without giving degrees. Sixteenth-century experts proposed locations from about 42°W to 49°W.

A Division Made Without the People Living There The treaty divided lands between two European powers, in the source's words "newly discovered lands outside Europe." The source does not mention the peoples who already lived there, and I did not find any account of their being consulted. Chapter 1 flagged the word "discovered," and I use the source's phrasing only to describe the document.

Later Changes

  • 1529: the Treaty of Zaragoza extended the division globally, establishing an antimeridian 297.5 leagues east of the Moluccas. Portugal received roughly 191 degrees and Spain roughly 169.
  • 1750: the Treaty of Madrid declared the Tordesillas framework superseded, establishing new borders between Brazil and Spanish America and acknowledging changing colonial realities.
What I Did Not Verify I did not find how Columbus won his backing, the terms he negotiated, the size and crew of the first fleet, or what other European states thought of the treaty. I also did not verify how the treaty relates to the papal bulls beyond the source's brief mention, and I did not check the claim that the Moluccas boundary favored Portugal. The chapter therefore gives the treaty's structure but not its diplomacy.

Hands-On Exercises

Exercise 1

Set out Columbus's four voyages with one fact each, and name one thing the source does not explain about the third.

→ Solution
Exercise 2

Explain Columbus's error about the Earth's size and say why the source's figures make the plan look more feasible than it was.

→ Solution
Exercise 3

Describe what the Treaty of Tordesillas divided and why it caused ongoing uncertainty, using the chapter.

→ Solution

Quick Reference

  • Columbus: four voyages 1492 to 1504; first left 3 August 1492, landfall 12 October (Guanahani/San Salvador)
  • Ships: Santa María (carrack, wrecked 25 December 1492), Niña and Pinta (caravels)
  • Error: Earth estimated at about 75% of its true size; Asia placed about 2,400 nautical miles west of the Canaries, roughly a quarter of the true distance
  • Treaty of Tordesillas: 7 June 1494; a meridian 370 leagues west of the Cape Verde islands; east to Portugal, west to Castile
  • Later: Zaragoza 1529 (Moluccas antimeridian); Madrid 1750 supersedes
  • Not covered: Columbus's backing, conditions in the settlements, the peoples' role