At York's castle, Richard, Edward, and Montague enter in disagreement. York enters and asks about their discussion. Richard and Edward ask their father about the crown, which York says they shall receive when Henry dies. They urge him to enjoy the throne now, for Henry shall surely outlive York. But York insists that he took an oath to let Henry rule untroubled. But Richard says it was not a legally binding oath, since it was not sworn before a magistrate. Therefore, he urges his father to fight for the crown.
York is easily convinced. He tells Montague to go to London to contact Warwick and other lords who support him. Meanwhile a messenger enters with news that the queen's armies are on their way to besiege York's castle. York sends Montague with even more haste and prepares to fight, when several of his relatives show up with their armies to resist the armies led by the woman general.
The Earl of Rutland, York's youngest son, and a tutor are on their way to York's castle when they encounter Clifford. Rutland begs for his life, asking Clifford to fight with his father instead of killing him. But Clifford is determined to kill Rutland to pay back York for having killed the elder Clifford. Killing all the members of the house of York and desecrating their tombs would not be enough to calm his ire, Clifford declares. Rutland begs again, saying Clifford has no cause to kill him, but Clifford sees reason enough and kills Rutland.
On the battlefield, York observes the deaths of some of his lords and the success of the queen's army. His army has been unable to beat back Margaret's forces. He predicts his demise as Margaret enters with Clifford, Northumberland, and Prince Edward. Clifford says York's day is over, but York insists that a phoenix will rise from his ashes to revenge him. Clifford is ready to kill York, but Margaret holds him back. Northumberland, Clifford, and York fight, and they capture York.
Margaret speaks to an imprisoned York, mocking his desire to be king. Where are his sons to protect him now, she asks. She shows him a handkerchief covered with Rutland's blood, which she offers him to use to dry his tears. When York doesn't show any emotion, she calls him a madman. York is silent, so she suggests that he will not speak unless he wears a crown. Her soldiers make a paper crown, and she puts it on his head, reminding him of the oath he made with Henry to disown Henry's son, an oath he would now try to break by attempting to regain the crown while Henry still lives. These are unpardonable faults, she says, and knocks the crown from his head.
York responds, bitterly accusing Margaret of being unnatural to be leading an army. He calls her evil, reminds her of her father's paltry claim to nobility and his poverty. Women, he says, have beauty, virtue, and the ability to govern themselves, but she has none of these attributes, and that makes her abominable. How can you be a woman, he asks, and yet dip a handkerchief in a child's blood and present it to a father to wipe his eyes? If weeping and raging is what she wants, then he will do both. York calls Margaret inhuman, while Northumberland observes that he feels sorry for York, seeing how much his sorrow affects him. Clifford and Margaret stab York, and he dies. Margaret orders York's head to be placed on the gates of the town of York.
At the end of 2 Henry VI, York killed Clifford's father. Clifford's grief at the fact that York didn't spare his aged father led him to swear he would kill even the youngest child of the house of York, which he accomplishes by murdering Rutland.
Margaret holds her lords off when they want to kill York, apparently because she wants to taunt him before she kills him. With a handkerchief dipped in Rutland's blood, she challenges him to mourn for his son while she charges him with having an upstart's desire for the throne. He accuses Margaret of having the opposite characteristics of everything that embodies femininity, which makes her a monster. Taking up arms was virtually unheard of for a woman in this time, though Margaret probably had heard of Joan of Arc, who led the forces in France at the time of Margaret's betrothal to Henry. While soldiering was an uncharacteristically masculine activity for a woman, Margaret's actions are driven by a stereotypically feminine desire to care for her son and assure his rightful future. York accuses her of behaving unnaturally, yet she nevertheless demonstrates a kind of "natural" tendency to defend her offspring to the death.
After escaping through many battles and debates through the prior two plays, York's luck finally runs out. Despite the fact that the contemporary title of this play was Richard Duke of York, York dies in the first act of the play. Theoretically he has won the right to the throne, though the legality of his agreement with Henry is debatable; yet he is unable to become king, and Henry outlives him. The ambiguous prediction of the spirits summoned by the Duke of Gloucester's wife in 2 Henry VI finally comes true, as a duke overcomes a king, yet the king outlives this duke. Now the focus of the York line shifts to his remaining sons, and their struggles.