What happens during the event at Cajamarca that is discussed in Diamond's Guns, Germs, and Steel?

The event at Cajamarca that Jared Diamond discusses in Guns, Germs, and Steel was the first meeting between the Inca emperor Atahuallpa and Francisco Pizarro and his invading army of Spaniards.  This meeting took place on November 16, 1532 and is discussed beginning on p. 68 of Diamond’s book.
Diamond says that Pizarro had 168 Spaniards with him at Cajamarca while Atahuallpa had 80,000 of his own warriors.  Even so, Diamond says on p. 68, Pizarro captured the Inca “within a few minutes” of the time when the two leaders met.  Diamond then uses Spanish sources to give many more details.  The details of what happened at the actual encounter/battle begin on p. 70.  Essentially, Pizarro planned to capture Atahuallpa.  He divided his forces and hid most of them at various places around the square in the town of Cajamarca.  According to the Spaniards (p. 72), Atahuallpa looked at the Bible and then threw it away, at which point the Spanish attacked.  The Spanish slaughtered the Native Americans, killing (according to the writer that Diamond quotes) something like 7,000 of them before night fell.  Diamond’s long quotation from the Spanish records ends on p. 74.
So, the best way to describe the event at Cajamarca is to say that it was a fight between 168 Spaniards and tens of thousands of Incas.  The Spanish apparently planned all along to kill the Native Americans (or were at least very ready to do so).  They seem to have used the religious “insult” as a pretext for the fight.  The Spanish routed the Incas decisively, killing thousands of them.  Diamond recounts this incident because he wants to think about why it was that the Spanish were able to defeat a force that was so much larger than their own.  He goes on to discuss this issue in the rest of Chapter 3 of Guns, Germs, and Steel.