The remains of a massive cypress tree sits inside a small plaza in Mexico City, surrounded by fencing and illuminated by four spotlights at night. An old sign explains its significance: “This is the tree where Hernán Cortés wept after being defeated by the Aztec defenders.”

We Mexicans call it El Árbol de la Noche Triste, or The Tree of the Sad Night, and learn about it since grade school from government-issued history textbooks. The story goes something like this: In March 1519, a couple of hundred Spaniards, led by a stubborn but resourceful man with some legal training named Hernán Cortés, appeared on the Gulf of Mexico coast. They established contact with the mighty Aztecs of central Mexico and, after