Not only did Patrick Henry structure his "Speech to the Virginia Convention" using the four parts of a classical argument, but he also used powerful rhetorical devices to persuade his listeners (who were wealthy and powerful delegates) to take action.
This speech's structure reflects that of a classical argument, which strengthens its sense of reasoning. In the first two paragraphs, Henry engages the audience, speaking highly of patriotism and reminding them of the duty they have "to God and our country." In the third paragraph, Henry develops his argument, asking the delegates to judge the intent of the British by their deeds, which are increasingly "warlike."
In the fourth paragraph, Henry moves into his counterarguments, acknowledging that some say that the American forces are too "weak" to "cope with so formidable an adversary." Henry responds to this claim by asserting that battles are not always won by the strong; instead, victories are often claimed by the "vigilant, the active, the brave." In his final paragraph, Henry gives a call to action, famously asking that the British "give [him] liberty or give [him] death." Henry masterfully used the structure of a classical argument to influence the delegates' decision.
Henry also uses rhetorical devices in this speech, making it increasingly persuasive. He appeals to the delegates' sense of pathos, or emotions, by calling them "very worthy gentlemen" in the opening line. He also engages a sense of pathos in this line:
For my own part, I consider it as nothing less than a question of freedom or slavery.
Juxtaposing the concepts of freedom and slavery engages a particular emotional response; he compares submission to the British as agreeing to enslavement.
Henry uses ethos, or an ethical appeal, various times throughout this speech. He speaks of "hope" and asks the delegates to consider the "painful truth." He calls the struggle "noble" and speaks highly of "liberty."
Of course, the final line of this speech is one of the most powerful lines ever spoken and has thus become symbolic of American independence.