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

In the relatively brief 1775 "Speech to the Virginia Convention," Patrick Henry poses over twenty rhetorical questions to his audience.  Generally, a rhetorical question is not asked because the speaker expects an answer; instead, the question is asked to try to engage the listener and emphasize a particular point. 

What Henry was hoping to accomplish in the speech was to persuade the members of the House of Burgesses and the Virginia colony as a whole to declare war against Britain. Others who spoke that day were advocating continued negotiation with Britain, but Henry believed negotiation had been tried for too long and was yielding no change in how the colonies were treated.

Throughout the speech, Henry repeats the point that the situation the Virginia colony is in is enslavement to a foreign master. He uses many metaphors and images of chains, and in his final rhetorical question asks the assembly: "Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?" He is appealing to the dignity and masculinity of the men of the assembly in hope that they will consider Britain's treatment a personal affront.