This whole time the disciples traveled with Jesus they were learning the art of war, how to advance the Kingdom amidst hostile men of all persuasions—religious, political, cultural, and Satanic.  He was showing them how a compassionate God-man fights during his time on earth: teaching, preaching, healing, feeling compassion, and boldly liberating those who were held captive and controlled by the god of this world and sin.  But now their residency was coming to an end.  The season of selection, association, and demonstration was giving way to the next phase:  delegation and supervision.  He looked at them and said, “The harvest is plentiful but the workers are few. Ask the Lord of the harvest, therefore, to send out more workers into his harvest field.”
Matthew 9:37 NIV 

Their "mission briefing" called by the Master Instructor went exactly like this: He called his disciples to Him and gave them authority to drive out evil spirits and to heal every disease and sickness. "As you go preach this message: 'The Kingdom of heaven is near.' Heal the sick, raise the dead, cleanse those who have leprosy, drive out demons. Freely you have received, freely give. I am sending you out like sheep among wolves. Therefore, be as shrewd as snakes and as innocent as doves. Now that is what I call a green light! With the full endorsement of the Supreme Commander, God's men were given:

• a sanction to fight (gave authority)
• a message to forward (preach this)
• targets to find (sick, dead, leper, demon possessed)
• power to free (to heal, raise, cleanse, and drive out) 
• a charge to feel (freely you have received, freely give)
• a metaphor to familiarize (sending you as sheep among wolves)
• two commands to fulfill (be shrewd and be innocent)

Imagine you are there. Which of these would send your neurons into high gear? A certain metaphor maybe?

Sheep among wolves you say? This means it's hostile now. Every instruction up to that point had to feel good to the disciples and then came the harsh reality of a Hot L.Z. (as in a Hot landing Zone). This condition of hostility would not change for these men until eleven were martyred and John died in exile. Jesus didn't provide false hope or codependent comfort. He gave them the straight poop about this campaign to rid the world of Satan's grip through Kingdom advance whenever and wherever possible. He didn’t say, "sheep among wolves for a while and then sheep among rabbits for a while." So since this is our present reality I want you to think "wolves" for a second.

• predatory carnivores that hunt in packs
• aggressive, greedy and cruel when they find their prey
• beautiful to look at but extremely dangerous
• wicked sense of smell
• extremely smart
• never want to be caught alone amongst a pack