Henry, now seen to be a wise and serious king, is assured by the Archbishop of Canterbury and the Bishop of Ely that he has a right to the French throne.
His decision to take the French crown is reinforced when ambassadors from the Dauphin bring him a contemptuous present, in the form of tennis balls.
As Henry and his associates prepare for France, he arraigns Cambridge, Scroop, and Grey as traitors. Meanwhile, Nym and Pistol quarrel while they make their preparations for war, with Bardolph trying to keep the peace. They learn of Falstaff’s death from the Hostess and the Boy, and bid her farewell.
The French lords discuss the arrival of the English, and receive Exeter with Henry’s demands, which are rejected. Pistol and his associates try to avoid the fighting, much to the disgust of the Boy, but they are forced into the front line by Captain Fluellen, who then enters into a discussion of military strategy with his fellow-captains Gower, Jamy, and Macmorris. Harfleur falls after Henry’s assault. Pistol has a sharp encounter with Fluellen.
The French King’s daughter, Katherine, has an English lesson from her maid, Alice, while the French lords discuss their impending victory over the English. They send their herald, Montjoy, to Henry, who rejects the offer to yield. The French boastfully prepare for battle. In the English camp, Henry disguises himself as an ordinary soldier and engages in discussion with some of the men. He tries to justify the King’s strategy in response to criticisms from Williams, who refuses to accept the disguised Henry’s account of the King’s motives.
Henry and Williams agree to challenge each other, if they live to see each other again, exchanging gloves by way of recognition. Henry then reflects on the responsibilities of kingship. The French, ebullient as ever, leave their camp for the battle of Agincourt. Henry rallies his troops, dismissing anxieties about their number. He rejects a further offer of surrender from Montjoy.
The battle begins. Pistol captures a French soldier, and obtains a ransom with the help of the Boy’s French-speaking ability. The French lords find themselves being defeated, but some of the French make a late rally into the English camp, and against the code of war kill the boys, much to Henry’s anger. Montjoy brings news of the French surrender.
Henry sees Williams, and gets Fluellen to wear Williams’ glove on his behalf, but defuses the ensuing quarrel as soon as it begins by explaining who it was that caused it. News arrives of great French losses and very few English ones. Fluellen meets Pistol, and reacts to his insults by making him eat the Welsh leek and giving him a beating.
The English and French kings and lords meet to discuss terms of peace. While the lords work out the details, Henry woos Katherine, who eventually agrees to marry him. The French accept the English terms, and Henry looks forward to a peaceful relationship between the two countries.