In Wales, at the castle of Owain Glyndwr, the leaders of the rebel armies have gathered to discuss strategy. The two most important members of the Percy family, Hotspur and Worcester, are there, along with Lord Mortimer (Hotspur’s brother-in-law, referred to in the play as his cousin). Their host, Glyndwr, is Mortimer’s father-in-law and the leader of the Welsh rebels. He believes strongly in the ancient Welsh pagan traditions of prophecies, omens, magic, and demons. He claims to be able to call spirits from hell, and he says that at his birth the earth shook and the sky was full of fire. Hotspur makes fun of the Welsh leader’s claims of magical power. Despite his best efforts, Mortimer cannot get his tactless brother-in-law to shut up. Hotspur mocks Glyndwr’s claim to be able to command the devil; Glyndwr then asserts that he has repelled Henry’s invasions three times. By the time the four actually get down to discussing strategy, Glyndwr is none too pleased with his youngest guest.

The men take out a large map of Britain and divide it up as they have earlier discussed: after they defeat King Henry, Glyndwr will get the western part of Britain—western England and all of Wales; Mortimer will get the southeast part of England, including London; Hotspur will get the northern part, home to his family. Hotspur begins to complain because he does not like the way that a river curves through his land, and he says that he will have the river straightened out. Irritated, Glyndwr tells Hotspur that he must not do so, and the two bicker again, although Glyndwr ends the dispute this time by giving in.

After Glyndwr leaves the room, Mortimer chides Hotspur for bothering Glyndwr. Hotspur says he is bored and annoyed with Glyndwr’s talk of prophecies and magic. Mortimer reminds him that Glyndwr is a powerful, courageous, and well-read man, and also possibly a dangerous magician. He points out that Glyndwr has been very tolerant of Hotspur’s youthful obnoxiousness. Anyone else, he warns, would have felt the force of Glyndwr’s anger already. Worcester agrees and urges Hotspur to mind his manners and show respect. Hotspur claims unconvincingly that he has learned his lesson.

Glyndwr brings in Mortimer’s and Hotspur’s wives; the four must say goodbye, for the men must ride off to meet their allies that very night. Lady Mortimer, Glyndwr’s daughter, cannot speak English, and Mortimer knows no Welsh. Lady Mortimer weeps for her husband, who speaks lovingly to her, and Glyndwr translates between them. Mortimer lays his head in her lap, and she sings the company a song in Welsh. Meanwhile, Hotspur and his wife, Lady Percy, bid each other farewell in a half-affectionate, half-fighting manner. By the time Lady Mortimer’s song is over, the formal contracts of agreement among the rebel leaders have been drawn up. The men sign them, and Mortimer, Hotspur, and Worcester then set forth. They are heading to Shrewsbury, near the English border with Wales, to meet the Earl of Northumberland (Hotspur’s father) and his ally, the Douglas of Scotland, who will bring with him a thousand soldiers. Glyndwr, meanwhile, will gather his army, which he plans to lead into England within two weeks.

Hotspur’s quick temper and insolence flare up once again in this scene: with a few rude words, he alienates the extremely powerful Owain Glyndwr, one of his family’s most important allies. By this point, Hotspur’s immaturity is apparent as the negative side of his boldness and sharp military instincts. As Worcester insightfully notes, Hotspur’s greatest asset—his boldness and quick temper—is also his worst flaw; he is valiant in battle but cannot manipulate or work with people behind the scenes. This flaw eventually proves a deadly weakness for Hotspur, since manipulation and diplomacy are among the greatest strengths of Prince Harry, his archrival. This tension emphasizes the importance the play places on understanding the qualities of true leadership.

This scene also provides us with a strong taste of Welsh culture and tradition, which Glyndwr embodies. The English regarded the ancient Welsh customs and supernatural traditions with mingled disdain and unease. On the one hand, they felt that a more advanced civilization (as they considered themselves) should have no fear of ancient superstitions. On the other hand, however, no one could be sure that the Welsh were not really magicians. This scene recalls the horror with which Westmoreland speaks, in Act I, scene i, about the ritualistic mutilations that the Welsh women performed upon the English dead.

Glyndwr himself is a fascinating mix of the Welsh and English worlds. As he rather sternly reminds the insolent Hotspur, he was “trained up in the English court” and speaks fluent English as well as his native Welsh (III.i.119); as Mortimer further notes, he is “exceedingly well read”—a quality associated with gentlemanliness and urban sophistication (III.i.162). But Glyndwr’s claims to be a magician able to summon demons, along with his insistence on the significance of the omens that he believes filled the sky and earth on the day of his birth, reflects his strong commitment to his pagan heritage. Even Mortimer implies that he believes in Glyndwr’s magic arts, testifying that Glyndwr is “profited / In strange concealments,” or supernatural skills (III.i.162–163).

Hotspur rudely trivializes Glyndwr’s claims to magic and justified patriotism. To Glyndwr’s boasts about defeating Henry’s attempted invasions and sending him home “[b]ootless,” Hotspur exclaims in mock surprise, “Home without boots, and in foul weather too!” (III.i.64–65). Given the gravity of the situation, Hotspur’s punning response at Glyndwr’s expense is inappropriate.

Mortimer’s inability to communicate with his own wife is a further manifestation of the cultural barriers between the English and the Welsh. Unlike Hotspur, however, Mortimer at least shows himself to be aware of the value of understanding other cultures and tongues, despairing, “O, I am ignorance itself in this!” when he cannot understand his wife (III.i.206). The presumably exotic song that Shakespeare has Lady Mortimer sing in Welsh would probably have established a sense of the foreign and the mysterious for an Elizabethan audience—a taste of the “irregular and wild” world that lay just beyond the bounds of late medieval and Renaissance English civilization (I.i.40).