URGENT! How can I stop my Barred Rock (Oreo) stop pecking all the other chickens?

[Red Banks]

Sometimes isolating the bully will change the pecking order of the flock. Oreo may come out of confinement to find she is at the bottom of the pecking order.... it would take more than a couple of days though.

 

[Mary's Backyard Chickens]

Here's a photo of Oreo tho.