In 1519, Hernan Cortes and his small army of conquistadors, driven by gold-lust, ambition and religious fervor, began the audacious conquest of the Aztec Empire. By August 1521, three Mexica emperors were dead or captured, the city of Tenochtitlan was in ruins and the Spanish had conquered the mighty empire. Cortes was smart and tough, but he was also lucky. Their war against the mighty Aztecs—who outnumbered the Spaniards by over 100-to-one—took fortunate turns for the invaders on more than one occasion. Here are some of the important events of the conquest.

02 of 10 March 1519: Malinche Joins the Expedition Mural by Diego Rivera, Mexican National Palace Cortes' first major stop in Mexico was the Grijalva River, where the invaders discovered a medium-sized town called Potonchan. Hostilities soon broke out, but the Spanish conquistadors, with their horses and advanced weapons and tactics, defeated the native people in short order. Seeking peace, the lord of Potonchan gave gifts to the Spanish, including 20 enslaved girls. One of these girls, Malinali, spoke Nahuatl (the language of the Aztecs) as well as a Mayan dialect understood by one of Cortes' men. Between them, they could effectively translate for Cortes, solving his communication problem before it had even begun. Malinali, or "Malinche" as she came to be known, helped Cortes as more than an interpreter: she helped him grasp the complex politics of the Valley of Mexico and even bore him a son.

03 of 10 August-September 1519: The Tlaxcalan Alliance Painting by Desiderio Hernández Xochitiotzin By August, Cortes and his men were well on their way to the great city of Tenochtitlan, the capital of the mighty Aztec Empire. They had to pass through the lands of the warlike Tlaxcalans, however. The Tlaxcalans represented one of the last free states in Mexico and they loathed the Mexica. They fought the invaders fiercely for almost three weeks before suing for peace in recognition of the Spaniards' tenacity. Invited to Tlaxcala, Cortes quickly made an alliance with the Tlaxcalans, who saw the Spanish as a way to finally defeat their hated enemies. Thousands of Tlaxcalan warriors would henceforth fight alongside the Spanish, and time and again they would prove their worth.

04 of 10 October 1519: The Cholula Massacre Nastasic / Getty Images After leaving Tlaxcala, the Spanish went to Cholula, a powerful city-state, a loose ally of Tenochtitlan, and home of the cult of Quetzalcoatl. The invaders spent several days in the marvelous city but began to hear word than an ambush was planned for them when they departed. Cortes rounded up the nobility of the city in one of the squares. Through Malinche, he berated the people of Cholula for the planned attack. When he was done speaking, he turned loose his men and Tlaxcalan allies on the square. Thousands of unarmed Cholulans were slaughtered, sending the message through Mexico that the Spaniards were not to be trifled with.

05 of 10 November 1519: The Arrest of Montezuma Internet Archive [Public domain] The conquistadors entered the great city of Tenochtitlan in November of 1519 and spent a week as guests of the nervous city. Then Cortes made a bold move: he arrested the indecisive emperor Montezuma, placing him under guard and restricting his meetings and movements. Surprisingly, the once-mighty Montezuma agreed to this arrangement without much complaint. The Aztec nobility was stunned, but powerless to do much about it. Montezuma would never again taste freedom before his death on June 29, 1520.

06 of 10 May 1520: The Battle of Cempoala Lienzo de Tlascala, Artist Unknown Meanwhile, back in Cuba, Governor Velazquez was still fuming at Cortes' insubordination. He sent veteran conquistador Panfilo de Narvaez to Mexico to rein in the rebellious Cortes. Cortes, who had undertaken some questionable legal tricks to legitimize his command, decided to fight. The two conquistador armies met in battle on the night of May 28, 1520, at the native town of Cempoala, and Cortes handed Narvaez a decisive defeat. Cortes gleefully jailed Narvaez and added his men and supplies to his own. Effectively, instead of regaining control of Cortes' expedition, Velazquez had instead sent him much-needed weapons and reinforcements.

07 of 10 May 1520: The Temple Massacre Codex Duran While Cortes was away in Cempoala, he left Pedro de Alvarado in charge in Tenochtitlan. Alvarado heard rumors that the Aztecs were ready to rise up against the hated invaders at the Festival of Toxcatl, which was about to take place. Taking a page from Cortes' book, Alvarado ordered a Cholula-style massacre of the Mexica nobility at the festival on the evening of May 20. Thousands of unarmed Mexica were slaughtered, including many important leaders. Although any uprising was certainly averted by the bloodbath, it also had the effect of enraging the city, and when Cortes returned a month later, he found Alvarado and the other men he had left behind under siege and in dire straits.

08 of 10 June 1520: The Night of Sorrows Library of Congress; Artist Unknown Cortes returned to Tenochtitlan on June 23 and soon decided the situation in the city was untenable. Montezuma was killed by his own people when he was sent out to ask for peace. Cortes decided to try and sneak out of the city on the night of June 30. The escaping conquistadors were discovered, however, and hordes of angry Aztec warriors attacked them on the causeway out of the city. Although Cortes and most of his captains survived the retreat, he still lost about half his men, some of whom were taken alive and sacrificed.

09 of 10 July 1520: The Battle of Otumba Mural by Diego Rivera The new leader of the Mexica, Cuitlahuac, tried to finish off the weakened Spaniards as they fled. He sent an army to destroy them before they could reach the safety of Tlaxcala. The armies met at the Battle of Otumba on or about July 7. The Spanish were weakened, injured and greatly outnumbered and, at first, the battle went very badly for them. Then Cortes, spotting the enemy commander, rallied his best horsemen and charged. The enemy general, Matlatzincatzin, was killed and his army fell into disarray, allowing the Spanish to escape.