Read the full text of Henry VI Part 3 Act 5 Scene 1 with a side-by-side translation HERE.
Warwick asks some messengers where Montague, George, and Oxford (or, more important, their troops) are. He gets the deets for each one. When he hears a drum, he thinks it's George, but it's actually Richard and Edward.
Edward asks Warwick who he calls king. Warwick says he'd rather Edward just be Duke of York. Henry is the king, and Warwick says he's the king's loyal subject.
Edward tells Warwick that Henry is actually in prison.
Warwick says he's not worried, because he's got backup.
Somerset and Montague enter with their men. Right on time.
George enters, and Warwick welcomes him.
Surprising everyone, George throws down his red rose and says he can't hate his own father's house. He apologizes to Richard and Edward for being fickle. They forgive him.