At the rebels’ camp in Shrewsbury, Hotspur and the Douglas argue with Worcester about whether they ought to attack Henry’s forces right away or hold off for a while. Worcester and Vernon urge them to wait: not all of the forces that Vernon will send have arrived yet, and since Worcester’s band of knights on horses has just arrived that day, the horses are still worn out. But Hotspur and the Douglas are both impatient to attack.

Sir Walter Blunt arrives in their camp, bearing an offer of peace from Henry. If Hotspur and his allies will state their grievances against Henry and disband their attack, he says, Henry promises that he will satisfy their desires and grant full amnesty to the rebels. Hotspur then launches into a long speech in which he describes his family’s dissatisfaction with Henry: when Henry himself had been the underdog several years before, trying to seize power from the king at the time, Richard II, the Percy family gave him invaluable help. Henry, then known as Henry Bolingbroke, had once been a mere cousin of the former king. Exiled by his royal cousin for flimsy reasons, Henry returned to England while King Richard was away fighting in Ireland. He originally claimed that he had only come to reclaim the title and inheritance that were due to him from his father, Richard’s recently deceased uncle, whose lands Richard had seized upon his death. Henry stayed, of course, to fight for the crown of England. Partly swayed by the influence and power of the Percy family, the common people of England and the nobles of -Richard’s court joined Henry’s faction, allowing him to take over power from Richard in a bloodless coup—though Richard was later assassinated in mysterious circumstances.

Now, King Henry seems to have forgotten the gratitude he owes the Percy family—the most recent example being his refusal to pay a ransom for Mortimer after Mortimer was captured in Wales. Blunt asks if he should take Hotspur’s words as a declaration of war; Hotspur replies that Blunt should return to Henry and await Worcester in the morning with the rebels’ decision. Hotspur suggests they may decide to accept Henry’s offer of amnesty after all.

Meanwhile, in York (in northern England), the Archbishop of York, an ally of Hotspur and the other rebels, speaks with a friend named Sir Michael. The archbishop gives Sir Michael urgent letters, -including one to the archbishop’s cousin Scrope and another to the Lord Marshal. He tells Sir Michael anxiously that the next day will be very important, stating that the “fortune of ten thousand men”- depends on the outcome of the battle that is to occur at Shrewsbury (IV.iv.9). He is very concerned, for he has heard that Henry’s forces are powerful and that with Northumberland, Glyndwr, and -Mortimer absent, the Percy forces will be too weak to emerge victorious.

Sir Michael bids the archbishop be optimistic, since the rebellion does have on its side powerful warriors like the Douglas, his son Mordake, Vernon, Hotspur, Worcester, and others. But the archbishop replies that the king has all the other finest warriors in the land, including the Prince of Wales (Harry), his younger brother, Prince John, Westmoreland, Blunt, and many more. The archbishop urges Sir Michael to make haste with the letters. Apparently, the archbishop plans to set up a contingency plan in case Henry wins at Shrewsbury. He knows that Henry is aware of his involvement in the uprising, and, if the rebels lose, the archbishop will be implicated in the conspiracy.

The heart of Act IV, scene iii is Hotspur’s recounting of the history behind the Percys’ grievances against King Henry. Shakespeare’s audience would have been familiar with the events that Hotspur describes, since they were then a matter of relatively recent history. Moreover, other plays of the era had related these events, including Shakespeare’s own Richard II, which appeared about a year or so prior to 1 Henry IV.

Hotspur’s accusations in this scene are somewhat hypocritical, since he seems to imply that his father, Northumberland, only helped Henry to power because he believed that Henry would not overthrow the rightful king (“he heard him swear and vow to God / He came but to be Duke of Lancaster” [IV.iii.62–63]). The reality is, of course, somewhat more complicated, however, and it seems that Northumberland and the other Percys must have known perfectly well from the outset that Henry wanted to become king. Their choice to throw their power behind Henry in a claim to lands being held by King Richard could owe only to their confidence that Henry would overtake Richard, for if Henry were to fail, they would face serious retribution from King Richard. The complexity of the characters’ mixed political motivations seems to cast doubt on Hotspur’s own claim that he and his family have gathered their current army only in order to preserve their own safety.

Hotspur’s statement that the rebels may decide to accept Henry’s offer of peace is rather unexpected given Hotspur’s generally warlike character. It is completely at odds with his vow in the preceding section to fight Harry to the death. It is also an important point to bear in mind when Shakespeare reveals, in Act V, that Worcester is keeping certain facts from Hotspur because he fears that his nephew will be inclined to settle the debate peacefully. Worcester, not wanting a peaceful solution, thus secretly squelches any opportunity for Hotspur to follow through on the rational impulse that he shows in this scene.

The Archbishop of York’s only appearance in 1 Henry IV occurs in this scene, whose purpose is to set up plot threads that extend into the next play in Shakespeare’s sequence—2 Henry IV. We do not learn much about what the archbishop’s letters contain, but their effects imply that plots are being laid that will continue to haunt Henry even after the Battle of Shrewsbury concludes. Indeed, when the battle has scarcely ended, in Act V, scene v, Henry must almost immediately divide and disperse his forces again—half northward toward York and Northumberland, where the archbishop and the one remaining Percy are arming themselves, and half to Wales to deal with Glyndwr and his rebels.