Jesus of Nazareth

How did the crowd react when Jesus identified Himself as "Jesus of Nazareth" (John 18:5)?
“They drew back and fell to the ground.” (John 18:6)

And then what did Jesus have to do?
Repeat Himself and insist that He is Jesus of Nazareth: Then He asked them again, “Whom are you seeking?” And they said, “Jesus of Nazareth.” Jesus answered, “I have told you that I am He." (John 18:7-8)

What did this crowd consist of?
“A detachment of troops, and officers from the chief priests and Pharisees.” (John 18:3) The original word translated into the phrase, “detachment of troops” is speira. It is Latin in origin and means “cohort,” which is one-tenth of a Roman legion (and the original word translated, "captain" (John 18:12), is chiliarchos, which means the commander of such a Roman cohort). Since a Roman legion comprised of 6,000 soldiers at full strength, this crowd included about 600 Roman soldiers, as well as "officers from the chief priests and Pharisees,” meaning the Jewish temple guards.

Why did trained Roman soldiers, as well as the Jewish temple guards draw back and fall to the ground and not believe Jesus the first time? And why had so many of them come?
To be lent that many Roman soldiers, the high priest would have had to claim to the Romans that Jesus was a dangerous rebel leader whose band posed a grave threat. This crowd had come expecting to battle dangerous rebels, not to make a simple arrest. Upon their arrival at the base of the mountain, they are about to ask an unarmed man if he’s seen the rebels and their leader, and the man declares, “I am He." (John18:5) So they are both taken aback and incredulous.