Acts 12:6-11 meaning

Luke, the author of Acts, continues to describe the lengths to which Herod has gone to secure Peter during his imprisonment:

On the very night when Herod was about to bring him forward, Peter was sleeping between two soldiers, bound with two chains, and guards in front of the door were watching over the prison (v. 6). 

Peter is in a seemingly hopeless situation. He just saw his old friend and ministry partner James beheaded, and he knows that his neck is next on the chopping block. Herod has set "four squads of soldiers to guard him" (v. 4), sixteen men in total, binding him with two chains to two soldiers on either hand, with more guards outside the cell. 

Peter was arrested years before by the Sanhedrin, but the Lord intervened and freed him and the other apostles. However, it is easy to imagine that in this circumstance, Peter thinks that this is it for him. For the first time in years, a fellow believer has been put to death. James the Apostle has been murdered (Acts 12:2). 

Peter was arrested during Passover, and so his mind likely has turned to Jesus's arrest and crucifixion, which also took place during Passover. At this point Peter has probably resigned himself to the fact that ultimately, the fate of he and the other church leaders will be much like Jesus's, Stephen's, and James's. Jesus Himself warned Peter that it would be so (Matthew 24:9, John 21:18-19).

But Peter does not seem afraid. He does not seem bothered by these circumstances. He is not fretting over dying. He is not wringing his hands, he is not pacing back and forth in his cell. He is sleeping. 

Peter's faith is on display in his sleeping. On the eve of his own execution, he has no apparent concerns. He has come to this place where he has watched God raise the dead, where he has seen miracles, where he has seen God do things that no man would ever imagine. And so he trusts and rests in God, and he realizes that regardless of "Whether I still have my head attached to me tomorrow or not, I am in His hands." 

Perhaps at this point Peter had learned the lesson that he wrote later in his church letter, known as 1 Peter:

"Therefore humble yourselves under the mighty hand of God, that He may exalt you at the proper time, casting all your anxiety on Him, because He cares for you."
(1 Peter 5:6-7)

We can see in this passage penned by Peter that he trusted God to exalt him in God's own timing if Peter would humble himself before God. In this case humbling himself meant being content if he was to die as a martyr. Part of Peter's apparent peace at his looming martyrdom might have been due to Jesus telling him to expect to be martyred (John 21:18-19). 

Peter was also one who desired to be great. So Jesus granted Peter's request, for true greatness comes through being a faithful witness for Christ, in spite of death, loss, or rejection. The Greek word translated as "witness" in the book of Revelation is "martys" from which we derive the English word "martyr" (Revelation 1:5). Jesus was a faithful witness because He overcame death, loss, and rejection by the world. Jesus promises to greatly reward all who follow in His footsteps by following His example (Revelation 3:21). 

And while God allowed Herod to behead the Apostle James, thus calling that faithful minister to be reunited with his Lord Jesus, God has more work for Peter on earth. While Peter laid there, sleeping in a cell chained to two guards, with many guards watching over the prison outside the door, God intervenes:

And behold, an angel of the Lord suddenly appeared and a light shone in the cell; and he struck Peter's side and woke him up, saying, "Get up quickly" (v 7). 

Peter was sleeping so soundly that the light of the angel of the Lord did not wake him. The angel had to hit Peter to stir him—he struck Peter's side. The angel commands Peter to rise. We know from verse 9 that Peter thought he was seeing a vision. We might surmise from this that visions like the animals dropped from heaven on a sheet seemed real (Acts 10:9-15). 

Clearly the guards chained to Peter did not wake, nor did anyone else. Only Peter, whom the angel struck and woke, sees the angel. Perhaps this is why he thought he was seeing a vision. No one else in the room was reacting to what he saw.

Immediately, Peter is released from his bonds:

And his chains fell off his hands (v. 7). 

The angel does not need to touch the chains, they simply drop from his wrists. 

Peter waits for the next command from the angel. He has been woken up and his chains have fallen, but he is otherwise still in the jail cell with sleeping guards all around.
The angel continues to herd Peter along into action:

And the angel said to him, "Gird yourself and put on your sandals." 

And he did so. 

Peter gets dressed and puts his shoes (his sandals) on.

The angel gives him further instructions:

And he said to him, "Wrap your cloak around you and follow me." (v. 8) 

Peter throws on his cloak and obeys:

And he went out and continued to follow. Peter is so confused at this point that he did not know that what was being done by the angel was real, but thought he was seeing a vision (v. 9). 

The angel leads him out of the cell, and none of the guards stir. They sleep, all the while the prisoner and his supernatural guide make their way through the prison. 

When they had passed the first and second guard, they came to the iron gate that leads into the city, which opened for them by itself (v. 10). Again, it is interesting that the angel's purpose is simply to tell Peter what to do, to lead him by word. The chains fell from his wrists by themselves, and the iron gate at the front of the prison opened for them by itself. It is not by the angel's hand that these obstacles are undone. God is removing barriers and bondage to free Peter, while the angel shines as a guiding light to take him back into the city.

They exit the prison, and they went out and went along one street, and immediately the angel departed from him (v. 10). The angel's job was done. He departed from Peter immediately. The divine jailbreak is complete. Peter is left standing alone in the street.

Here he seems to fully wake up, to realize it had all been real:

When Peter came to himself, he said, "Now I know for sure that the Lord has sent forth His angel and rescued me from the hand of Herod and from all that the Jewish people were expecting." (v. 11).

He came to himself, meaning he came to his senses, and saw that the entire rescue from the prison had truly happened, that he knew it for sure, and attributed it to God. It was the Lord who sent the angel and rescued him. It was from the hand of Herod that he was delivered; his imprisonment, as well as the intended outcome of that imprisonment—Peter was rescued from all that the Jewish people were expecting. They were expecting to see Peter executed, just as James had been. But it was not Peter's time to go. The Lord has more for him to do.