Historians date the start of the Wars of the Roses to 1455, to this battle at St. Albans. Shakespeare gives the real start point not to a political act but to a private grief: Young Clifford standing over his father's body and announcing that his heart has turned to stone. The speech is remarkable because it is not performed in rage — it is reasoned. Young Clifford makes an argument: York spares no old men; therefore he will spare no children. Grief is converted into logic. And the Medea reference is not hyperbole for him — it is a statement of intent. In Henry VI Part 3, Young Clifford kills the young son of York exactly as promised, mocking him before the killing. What Shakespeare is doing in this speech is showing that the Wars of the Roses is not primarily a constitutional crisis or a dynastic dispute. It is a cycle of personal grief and revenge, handed down from fathers to sons, made permanent by the moment a grieving man decides that pity is a weakness he can no longer afford.

The prophecy 'let him shun castles' was delivered in Act 1 by a spirit conjured through black magic. Somerset dismissed it, Henry used it to destroy Gloucester, and everyone forgot about it. Shakespeare has not. The first stage direction in this scene is: 'The sign of the Castle Inn is displayed.' The playwright puts the prop onstage deliberately, lets it hang there through York's combat with Clifford and Young Clifford's entire stone-heart speech, and then has Richard kill Somerset directly under it. Richard's commentary — 'For underneath an alehouse' paltry sign, the Castle in Saint Albans, Somerset hath made the wizard famous in his death' — is an act of theatrical gloating. The irony is multilayered: Somerset died under a castle, as predicted, but the castle was an alehouse sign. The supernatural is vindicated, but via the most mundane instrument available. Shakespeare is being funny and horrifying simultaneously — the prophecy is right, and what makes it right is a painted board over a pub door.

Richard of Gloucester is probably fourteen or fifteen in this scene. He has had minimal stage presence in 5-1 — a few lines, aggressive but unremarkable. Here he kills Somerset and delivers six lines. Of those six lines, the last is the one that matters: 'Priests pray for enemies, but princes kill.' It is a rhetorical formula (priests do X, princes do Y) that functions as a personal manifesto. Richard is not saying what princes should do; he is saying what he will do, and he is marking himself as someone who has already decided that ordinary moral categories don't apply to him. This is the seed of Richard III — a man who by Richard III will be soliloquizing about his own villainy with the same cold pleasure he shows here. What makes it chilling is not the content but the tone: he is not rationalizing. He is not in distress. He is perfectly calm, admiring his own sword, announcing his philosophy of action as if it were obvious. It is.

Old Clifford's exchange with York before they fight is a small masterpiece of the chivalric code that this play is in the process of destroying. Both men compliment each other's valor. York says he could love Clifford if he weren't his enemy. Clifford says York's prowess would earn esteem if it weren't in treason. They are adversaries who recognize each other as honorable men on opposite sides — the medieval ideal of noble combat. Then Clifford dies in four lines with a French proverb. His son's response is to vow to cut York infants to pieces. The structural point Shakespeare is making is exact: the old honorable war ends with Old Clifford's death, and the new savage war begins with Young Clifford's vow. The chivalric world and the vendetta world cannot coexist, and the scene shows precisely when one ends and the other begins.