Stolen Continent describes the episode this way:
Cortes' new Tlaxcalan allies pleaded with him not to go through Cholula, arguing that the city was not a safe place for them. After careful consideration, Cortes decided to go, and took with him over 100,000 Tlaxcalan porters and soldiers. When the Conquistadors arrived, the Cholulans saw the heavily armed Tlaxcalans and protested to Cortes that their old rivals would not be welcomed into their city. Cortes ordered the Tlaxcalans to camp outside the city, while the Spanish soldiers were welcomed and treated to bountiful feasts...What a bad, bad man, no? The peaceful, smiling Chololans, who just wanted to be friends*, all murdered by those naughty Spaniards without so much as a butter knife with which to defend themselves. At least that's what Cortes' modern detractors would have you believe.
While in Cholula, Cortes' Nican Tlaca interpreter, known to many as La Malinche, was supposedly approached by an old woman who told her that the Cholulans were planning to attack the Spaniards. Cortes "questioned" a local inhabitant who corroborated Malinche's story-undoubtedly after being tortured by the Spaniards. Cortes seized upon this situation as an opportunity to "punish" the Cholulans. He did this by ordering all the "nobles and leading citizens" of the city to gather together at the temple of Quetzalcoatl for a speech he wished to give them. According to most sources, 3000 unarmed Cholulans were gathered together when the Spaniards cowardly attacked them - killing them all.
But as is usually the case, there is significantly more to the story. So let's let's bring in a few facts that might allow us to understand events from Cortes' point of view, from inside an enormous walled city, 500 men and a few porters against 100,000 increasingly hostile natives:
- Upon his arrival, Cortes and his men were fed a good meal. They have now been inside assigned quarters for three days and his hosts have brought no food - in fact they have stopped visiting him altogether. The only official visits he gets are from Montezuma's ambassadors.
- The royal road upon which he expected to leave has been blocked, and a new road is being cleared which leads toward an unknown end.
- Pits are being dug in the streets, the bottoms of which are fit with sharp spikes. They are covered over with dirt so they cannot be seen.
- The flat roofs of temples and houses have piles of boulders placed on them.
- Wooden barricades are erected in the streets.
- An army outnumbering him 50-1 arrives outside the town.
- Human sacrifice is performed, an act which has acted as a prelude to war in several places.
- All the women and children are moved out of the city.
- Soldiers outside the windows are mocking, describing how they will be eating the Spaniards with "tomatoes and chilis" quite soon.
So was his resultant destruction of the primary men of the town an unwarranted massacre? Or was Cortes, knowing that war was coming, justified in launching a pre-emptive strike? Your mileage may vary.
* With a great big hug and kiss from me to you. Won't you say you love me too?
** According to Diaz, the old woman, seeing how rich and good-looking Marina was, proposed marriage on behalf of her son. As she was to soon be a widow anyway, why not?