But in their eagerness to be first in the square, the Spaniards had pressed on, none caring to stop to see that the allies carried out the order.

So, taking position after position, they pressed on until they were close to the square.
Suddenly the horn of Guatimozin, the emperor, sent forth a piercing note from the summit of a temple.

As if by magic, the retreating Aztecs turned and fell on their pursuers; while swarms of warriors from the adjoining streets, lanes, and corners attacked the advancing column.
Taken completely by surprise, bewildered by the suddenness and fury of the onslaught, appalled by the terrific war yells, smitten down by the rain of missiles from the Aztecs, the Spaniards fell into confusion, and were swept down the street like foam on the crest of a wave.

In vain their leaders attempted to rally them.

Their voices were drowned in the din, and their followers, panic stricken, now thought only of preserving their lives.
On they came, until they reached the edge of the cut.