Far be the thought of this from Henry’s heart,
To make a shambles of the Parliament House.
Cousin of Exeter, frowns, words, and threats
Shall be the war that Henry means to use.
(1.1.70–73)

When the duke of Exeter suggests killing the duke of York, Henry speaks these lines insisting that he will manage the situation by talking it out. Of course, as Part 1 and Part 2 of the Henry VI sequence has amply shown, the king’s words have almost never proven effective in commanding anyone to do anything. Not only does this moment remind us of the weakness of his authority, but it also alerts us to the play’s thematic concern with the more general efficacy of language—particularly in the context of conflict.

KING LOUIS
Then further, all dissembling set aside,
Tell me for truth the measure of his love
Unto our sister Bonnë.
WARWICK            Such it seems
As may beseem a monarch like himself.
Myself have often heard him say and swear
That this his love was an eternal plant,
Whereof the root was fixed in virtue’s ground,
The leaves and fruit maintained with beauty’s sun,
Exempt from envy but not from disdain,
Unless the Lady Bonnë quit his pain.
(3.3.119–28)

This exchange takes place during Warwick’s mission to arrange Edward’s marriage to King Louis’s sister, Lady Bonnë. As an ambassador, he takes the initiative of making flowery promises of Edward’s love for the king’s sister-in-law. His honeyed words do indeed prove effective, such that the king shows him more favor than Margaret and agrees to the engagement. However, the rhetorical force of Warwick’s speech backfires when news arrives that Edward has already gone ahead and married someone else. Given the many of the promises and vows made and broken in this play, the audience learns to anticipate that, however they may be intended at the time of their utterance, words often turn out to have the opposite effect.

Lords, knights, and gentlemen—what I should say
My tears gainsay; for every word I speak
You see I drink the water of my eye.
Therefore, no more but this: Henry your sovereign
Is prisoner to the foe, his state usurped,
His realm a slaughterhouse, his subjects slain,
His statutes cancelled, and his treasure spent—
And yonder is the wolf that makes this spoil.
You fight in justice; then, in God’s name, lords,
Be valiant, and give signal to the fight!
(5.4.73–82)

These lines constitute the final speech Margaret delivers to her troops before they plunge into the final battle with Edward’s army. Her heightened rhetoric is carefully modulated and designed to produce a powerfully rousing effect among her soldiers. However, there is also a cruel irony at work in this speech, which Shakespeare uses to close act 5, scene 4. The irony becomes apparent as the next scene opens with the final battle already over, with Margaret and her son now standing chastened in court before the victorious King Edward IV. Thus, for all the power of her words, they have accomplished nothing. Even so, Richard recognizes that Margaret’s rhetoric is indeed dangerous. This is why he wants to kill her, and why, when Edward stays his hand, he asks, “Why should she live to fill the world with words?” (5.5.43).