my rooster is attacking my hen

[GRIMREAPER1981]

hi i just got five chickens 1 rooster and 4 hens im new to this and dont understand why my flock turned on one hen

 

[RedRoosterFarm]

pull the hen out and let her get strong and then put her back in. Maybe that will work?

 

[laughaha]

Is it the rooster being really rough with a favorite hen? If so pull the rooster and get one that is a gentleman.
Is it the whole flock attacking one hen? If so pull the hen and put her in isolation and check her over really well to see if she is injured or sick.
What are you feeding them? I would give them BOSS (black oil sunflower seeds), scrambled eggs and vitamins (no iron) in addition to their normal feed to see if they have a nutritional deficiency and are cannibalizing the lowest on the totem pole.
Are they really cramped in their enclosure?