In his speech to the Virginia Convention, Patrick Henry's aim is to win over his audience to his point of view, and accordingly he uses many rhetorical devices commonly used to increase an orator's powers of persuasion.
At the beginning of the speech, he uses anaphora to suggest to his audience that he is a reasonable man and aware of the broad picture—"different men often see the same subject in different lights." Anaphora is a form of parallelism in which the same words are repeated at the beginning of successive phrases. Other examples of this in this speech include "We have petitioned; we have remonstrated; we have supplicated . . . " and the subsequent sentence "Our petitions have been slighted; our remonstrances . . . " The most famous example of this type of parallelism comes in the closing line, "give me liberty or give me death!" which is also, arguably, an example of apostrophe, or appeal to "Almighty God."
Another form of parallelism, epistrophe, can be seen in such phrases as "The War is inevitable and let it come! I repeat, sir, let it come." In epistrophe, the same words are repeated at the ends of successive phrases in order to emphasize that part of the phrase.
Henry also makes great use of rhetorical questions in this speech. In several places, he strings one rhetorical question after the other ("Are fleets and armies . . . ? Have we shown ourselves . . . ?" "Is it that insidious smile . . . ?" etc). A rhetorical question in itself is a device intended to foster a sense of agreement and accord between speaker and listener; in asking one after another, the questions have a cumulative effect; it becomes increasingly obvious to the listener that there are numerous questions to which the answers must be obvious. This could also be considered an example of enumeratio (making a point by overwhelming the listener with detail).