Each year, the United States honors the explorer Christopher Columbus with a federal holiday, and many Americans incorrectly believe it’s because he discovered our country.

He didn’t.

Columbus made four trips across the Atlantic Ocean from Spain: in 1492, 1493, 1498 and 1502.

He was determined to find a direct water route west from Europe to Asia, but he never did.

Instead, he stumbled upon the Americas, which he did not discover, nor was he even the first European to visit the “New World.” (Viking explorer Leif Erikson had sailed to Greenland and Newfoundland in the 11th century.)

Though he did not really “discover” the so-called New World—millions of people already lived there—his journeys marked the beginning of centuries of exploration and colonization of North and South America.

At the end of the 15th century, it was nearly impossible to reach Asia from Europe by land.

The route was long and arduous, and encounters with hostile armies were difficult to avoid.

Portuguese explorers solved this problem by taking to the sea: They sailed south along the West African coast and around the Cape of Good Hope.

But Columbus had a different idea: Why not sail west across the Atlantic instead of around the massive African continent?

The young navigator’s logic was sound, but his math was faulty.

He argued (incorrectly) that the circumference of the Earth was much smaller than his contemporaries believed it was; accordingly, he believed that the journey by boat from Europe to Asia should be not only possible, but comparatively easy via an as-yet undiscovered Northwest Passage.

He presented his plan to officials in Portugal and England, but it was not until 1492 that he found a sympathetic audience: the Spanish monarchs Ferdinand of Aragon and Isabella of Castile.

Columbus wanted fame and fortune.

Ferdinand and Isabella wanted the same, along with the opportunity to export Catholicism to lands across the globe. (Columbus, a devout Catholic, was equally enthusiastic about this possibility.)

Columbus’ contract with the Spanish rulers promised that he could keep 10 percent of whatever riches he found, along with a noble title and the governorship of any lands he should encounter.

On August 3, 1492, Columbus and his crew set sail from Spain in three ships: the Niña, the Pinta and the Santa Maria.

On October 12, the ships made landfall—not in the East Indies, as Columbus assumed, but on one of the Bahamian islands, likely San Salvador.

For months, Columbus sailed from island to island in what we now know as the Caribbean, looking for the “pearls, precious stones, gold, silver, spices, and other objects and merchandise whatsoever” that he had promised to his Spanish patrons, but he did not find much.

In January 1493, leaving several dozen men behind in a makeshift settlement on Hispaniola (present-day Haiti and the Dominican Republic), he left for Spain.

He kept a detailed diary during his first voyage.

Christopher Columbus’s journal was written between August 3, 1492, and November 6, 1492 and mentions everything from the wildlife he encountered, like dolphins and birds, to the weather to the moods of his crew.

More troublingly, it also recorded his initial impressions of the local people and his argument for why they should be enslaved.

“They … brought us parrots and balls of cotton and spears and many other things, which they exchanged for the glass beads and hawks’ bells,” he wrote. “They willingly traded everything they owned … They were well-built, with good bodies and handsome features …They do not bear arms, and do not know them, for I showed them a sword, they took it by the edge and cut themselves out of ignorance. They have no iron …They would make fine servants … With fifty men we could subjugate them all and make them do whatever we want.”

About six months later, in September 1493, Columbus returned to the Americas.

He found the Hispaniola settlement destroyed and left his brothers Bartolomeo and Diego Columbus behind to rebuild, along with part of his ships’ crew and hundreds of enslaved indigenous people.

Then he headed west to continue his mostly fruitless search for gold and other goods.

His group now included a large number of indigenous people the Europeans had enslaved.

In lieu of the material riches he had promised the Spanish monarchs, he sent some 500 enslaved people to Queen Isabella.

The queen was horrified—she believed that any people Columbus “discovered” were Spanish subjects who could not be enslaved—and she promptly and sternly returned the explorer’s gift.

In May 1498, Columbus sailed west across the Atlantic for the third time. He visited Trinidad and the South American mainland before returning to the ill-fated Hispaniola settlement, where the colonists had staged a bloody revolt against the Columbus brothers’ mismanagement and brutality.

Conditions were so bad that Spanish authorities had to send a new governor to take over.

Meanwhile, the native Taino population, forced to search for gold and to work on plantations, was decimated (within 60 years after Columbus landed, only a few hundred of what may have been 250,000 Taino were left on their island).

Christopher Columbus was arrested and returned to Spain in chains.

In 1502, cleared of the most serious charges but stripped of his noble titles, the aging Columbus persuaded the Spanish crown to pay for one last trip across the Atlantic.

This time, Columbus made it all the way to Panama—just miles from the Pacific Ocean—where he had to abandon two of his four ships after damage from storms and hostile natives.

Empty-handed, the explorer returned to Spain, where he died in 1506.

Today, Columbus has a controversial legacy—he is remembered as a daring and path-breaking explorer who transformed the New World, yet his actions also unleashed changes that would eventually devastate the native populations he and his fellow explorers encountered.

This article first appeared on History.com.