Hernán Cortés, who led arguably the most fascinating, most consequential, and most harrowing special operations campaign in history, was born in Medellin, Spain, seven years before the first New World voyage of Christopher Columbus. As seems to be common for historical figures renowned for their military accomplishments in later life, he is often described as having been small and weak as a boy. When he was 14, his father, a retired infantry officer, sent him off to a live with an uncle, study Latin, and prepare for a career as a notary and lawyer.

But he was apparently a restless young man, and after a couple of years during which he actually did learn enough law to be of use later in his career as a conquistador (with a need to legally defend his actions), he went back to Medellin, where he soaked up stories of the New World and decided to go there. His family helped him make arrangements to sail with a relative, but young Hernando injured himself while hastily escaping from the window of a married woman he’d been, uh, visiting, and his departure was postponed. After a year of wandering and hanging out and probably getting in more trouble, he finally departed for Hispaniola in 1504. He did well in the capital of the Hispaniola colony as a landowner, and he served as a notary. But Cortés had a restless nature and a desire for action, and when expeditions were raised to conquer the rest of Hispaniola, and then Cuba, Cortés was among those eager for the fight.

It was during the conquest of Cuba that Cortés began his rocky relationship with Diego Velazquez, who became governor of the newly conquered country. In Hispaniola and Cuba, Cortés had greatly impressed Velazquez, and he was well rewarded with land grants and slaves, as well as a high position for a man in his mid twenties. Cortés had it made. The colony was sure to grow and as an early colonist, he’d prosper as the colony grew. Velazquez appointed Cortés his secretary and Cortés also became a municipal magistrate and labor contractor for his slaves. He prospered and gained power and influence, and learned how to manage people and affairs. He also flirted with political trouble, which made Governor Velazquez nervous about his popularity. And Cortés was still flirting with the ladies—including a couple of the governor’s sisters-in-law.

Diego Velazquez.

In the spring of 1518, Juan de Grijalva, a relative of Velazquez and friend of Cortés, led an expedition along the eastern coast and islands of Mexico. This was the second exploration party to venture forth from Cuba. The first expedition, under command of Francisco Hernandez, was not a total disaster, but it was a terrible ordeal filled with costly clashes with warlike locals and a lack of fresh water. In both of the early expeditions, the Spanish were surprised to find a material culture far more developed than could be found in Hispaniola and Cuba, and they were deeply shocked by the evidence of cannibalism and human sacrifice almost everywhere that there were people.

While Grijalva was exploring, Cortés lived in his house. After the expedition, when Velazquez decided to appoint Cortés to lead another exploration and colonizing expedition—this time into the interior of Mexico—Cortés used Grijalva’s house as a recruiting center, where he enlisted some of the men who had been with Grijalva on the previous expedition. Among the veterans of the Hernandez and Grijalva expeditions who signed on with Cortés was Bernal Diaz, a stalwart soldier who would eventually write the classic firsthand account of this amazing campaign, “The Conquest of New Spain.”

Cortés, recently married to one of Valazquez’s sisters-in-law, Catalina, went into debt preparing for this command. He was diligent and popular, with a good martial reputation stemming from the conquests of Hispaniola and Cuba, and a gift for persuasion. Sua sponte, volunteers flocked to him. Ships and crews were made ready. Supplies and soldiers, carpenters, priests, and a few cannons were embarked. There were only a few horses—most sources say 12 or 13—but there were plenty of willing horsemen. Charts and maps, food and water, weapons, powder, and medicine were shipped. Two captive young Maya men that the Hernandez expedition had kidnapped, adopted, and taught some Spanish were brought aboard to serve as interpreters. These interpreters didn’t exactly work out as planned. Ungrateful and disloyal wretches, one of them would die and the other would abscond as soon as he was on land where people spoke his own language. Kidnapped people can often be so ungrateful.

Cortés was preparing to cast off and join the rest of the fleet at another Cuban port when word came that old jealousies had risen up in Governor Velazquez, and that he had decided to rescind the commission he’d granted Cortés. Velazquez was eager to gain the most coveted status symbol a colonial governor of that era could attain—a terra firma mainland colony to add to his wealth and prestige. There was already a terra firma Spanish colony on the mainland, in Panama, and Bernal Diaz and his buddies had lived there before going to Cuba. Governor Velazquez wanted such a colony, but he did not want to give Cortés any share of the glory. When he learned that the governor was no longer supporting him, Cortés did the sensible thing: He mutinied. After uniting his little fleet, he put to sea and headed for Mexican waters.

Cortés left Cuba with 11 ships, approximately 600 men (including crews for the ships), a few small cannons, an unknown number of matchlock firearms that weren’t usable in rain or high humidity, 12 or 13 horses, and plenty of crossbows, pikes, and swords. Both horses and guns were initially very useful for the purpose of instilling “shock and awe” in opponents, but those opponents—and even the allies of the Spanish started out as opponents—soon learned the limits of the guns, and discovered that, in the right hands, the wooden Mexican sword edged with obsidian was capable of decapitating that fearsome new animal, the horse. At this stage of Old World weapons technology, crossbows were still more reliable and accurate than guns.