Why did Patrick Henry use rhetorical questions in his "Speech to the Virginia Convention"?

Rhetoric is the art of persuasion. As such, it's inevitably a very important component of public speaking, especially during periods of great political tumult. Patrick Henry's famous speech to the Virginia Convention certainly falls into this category. Quite a large number of delegates to the Convention still thought it possible to reach some kind of amicable settlement with the British. Henry's speech was a largely successful attempt to disabuse such men of what he regarded...

Rhetoric is the art of persuasion. As such, it's inevitably a very important component of public speaking, especially during periods of great political tumult. Patrick Henry's famous speech to the Virginia Convention certainly falls into this category. Quite a large number of delegates to the Convention still thought it possible to reach some kind of amicable settlement with the British. Henry's speech was a largely successful attempt to disabuse such men of what he regarded as their naivety. 

Rhetorical questions are not posed to glean opinions; rather they're a way of forcing each member of a speech's audience to ask themselves the question being raised:

"Are fleets and armies necessary to a work of love and reconciliation?"

Ask yourself this question, says Henry, if the British really want peace, then why are they sending more ships and troops to America? Henry emphatically answers his original question in the negative, but he's also hoping that some of the waverers in the Convention will arrive at the same conclusion.

"The war is actually begun! The next gale that sweeps from the north will bring to our ears the clash of resounding arms! Our brethren are already in the field! Why stand we here idle? What is it that gentlemen wish? What would they have? Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?"

Henry's using a clever rhetorical strategy here. He's presenting his audience with a fait accompli. The war has already begun; the only question now is what are we going to do about it. Are we going to just stand around doing nothing, or are we going to fight?  Do we want a nice easy life at the cost of being slaves? Using such black-and-white rhetorical questions to frame the issue presents the assembled delegates with a stark choice and makes it hard for them to oppose Henry's radical position.