What punishment was threatened in the Roman army for the sentry who fell asleep at the post?

The Roman Empire was a warlike power that lived by capturing foreign territories. She was famous for her unbending will and unbreakable firm discipline. When going on a campaign, the troops often stopped in camps for the night. To avoid being caught off guard while they were sleeping, sentries were posted. Without the sentries, they would be threatened with death, so if the sentry falls asleep, all of his brothers may perish. The punishment for a sentry who fell asleep while fulfilling his duty is death without a chance for pardon.