In Gaultree Forest in Yorkshire, the leaders of the rebel army--the Archbishop of York, Mowbray, and Hastings--have arrived with their army. The Archbishop tells his allies he has received a letter from Northumberland in which he says he will not be coming to their aid.
A soldier, returning to the camp from a scouting mission, reports that King Henry IV's approaching army is now barely a mile away. The army is being led by Prince John, the king's younger son; the king, who is sick, is still at Westminster. The scout is immediately followed by the Earl of Westmoreland, an ally of King Henry who has been sent as a messenger. Westmoreland accuses the Archbishop of improperly using his religious authority to support rebellion; the Archbishop replies that he did not want to, but he felt he had no choice, since King Henry was leading the country into ruin and the rebels could not get their complaints addressed. Westmoreland tells the rebels that Prince John has been given full authority to act in the king's name and is willing to grant their demands if they seem reasonable. The Archbishop gives Westmoreland a list of the rebels' demands, and Westmoreland leaves to show it to Prince John.
While the rebels wait for Westmoreland to return, Mowbray voices his fear that, even if they do make peace, the royal family will only be waiting for an opportunity to have them killed. However, Hastings and the Archbishop are sure that his fears are groundless.
Westmoreland returns and brings the rebels back with him to the royal camp to speak with Prince John. The prince says that he has looked over the demands and that they seem reasonable; he will grant all the rebels' requests. If they agree, he says, they should discharge their army and let the soldiers go home.
Very pleased, the rebel leaders send messengers to tell their soldiers that they can go home. They and Prince John drink together and make small talk about the upcoming peace. However, as soon as word comes from the rebels' messengers that their army has been scattered, Prince John gives an order to arrest Hastings, Mowbray, and the Archbishop as traitors. When they ask how he can be so dishonorable, Prince John answers that he is not breaking his word: he promised to address their complaints, and he will. However, he never promised not to kill the rebels themselves. He then gives orders for the rebels to be taken away and executed.
Meanwhile, elsewhere in the forest, one of the departing rebels--Sir John Coleville of the Dale--runs into Falstaff, who has finally made it to the field of battle. Recognizing Falstaff, Coleville surrenders to him. (Most people are now afraid of Falstaff because they falsely believe that he killed the famous rebel Hotspur at the Battle of Shrewsbury.) Prince John enters the scene and Falstaff presents his captive to him. Westmoreland appears to tell the Prince that the army is withdrawing; Prince John sends Coleville off with the other rebels to execution, and he announces he will return to the court in London because he hears his father is very sick. Falstaff heads off to Gloucestershire in order to beg some money from Justice Shallow.
Prince John's behavior in these scenes is, at best, underhanded and, at worst, tremendously dishonorable. He effectively lies to the rebels, telling Mowbray, Hastings and the Archbishop that he will concede to their demands, and then he reneges on his promise as soon as they have trustingly sent away their troops. The technicality that he uses to justify his action--the fact that he promised to address the rebels' complaints, not to ensure their safety--seems morally questionable. Prince John seems to go out of his way to convince the rebels that he means them no harm, repeatedly saying things like "Let's drink together friendly and embrace / That all their eyes may bear the tokens home / Of our restored love and amity" (63-65). That Hastings, Mowbray, and the Archbishop would have taken this as a promise of forgiveness seems obvious.
Prince John comes across as a much more treacherous character than any of the rebels over whom he claims moral authority. However, if we begin by assuming, as many during the Middle Ages did, that the king and the royal family are always right and have the authority of God himself behind them, then anyone who rises against them is clearly in the wrong. The royal family, thus, has the right to defeat them by any means necessary.
This line of thinking is related to the idea of the "divine right" of kings. It is an idea with obvious political value for rulers and one that was popular in the Middle Ages; the Renaissance was just beginning to question this assumption. It is obvious that at least some of King Henry's followers subscribe to this idea. When the Archbishop challenges Prince John's duplicity by asking, "Is this proceeding just and honorable?" Westmoreland replies by asking, "Is your assembly so?" This is the only answer that either he or John makes to the rebels' accusations that Prince John has broken his oath. Answering the questions only with another question, Westmoreland implies that Prince John's behavior is not wrong because it has corrected a previous wrong (i.e., "two wrongs make a right").
This concept of honor may be good enough for Prince John, and it may have been what some of Shakespeare's audience--including his ruler, Queen Elizabeth--wanted to hear. Shakespeare, however, seems to have been ambivalent about it; he has Falstaff voice his reservations about Prince John's behavior in his closing speech in IV.iii. In typical Falstaff style, he goes off into a very long, complex, and witty speech about a seemingly trivial topic--this time, wine--and expands it into a discussion of abstract truths that apply to the situation at hand.
In praising the virtue wine has in making men witty, Falstaff brings forth the virtues of a value system different from that of the king and his followers. He criticizes Prince John, in a somewhat worried tone, wishing that Prince John had "wit," for it would be "better than your dukedom. Good faith," he goes on, "this same sober-blooded boy doth not love me, not a man cannot make him laugh... There's never none of these demure boys come to any proof... They are generally fools and cowards" (84-93). Falstaff humorously blames Prince John's defects on his refusal to drink wine, but he also makes a valid criticism of Prince John's frightening lack of a sense of humor and strange version of "honor," which seems to be utterly lacking in human compassion. Falstaff knows, too, where Prince John got these bad qualities: from the leader of the state himself, King Henry IV. Even Prince Hal, he adds, is only valiant because "the cold blood he inherited of his father he hath... tilled, with excellent endeavor of drinking" (114-119).