The most famous expression from Patrick Henry's speech to the Virginia Convention—“Give me liberty or give me death”—perfectly encapsulates the importance that he and many other Americans at the time gave to liberty. The American colonists believed themselves to be blessed with the same liberties of freeborn Englishmen, and they were therefore outraged at what they saw as the tyrannical behavior of successive British governments, which they regarded as a threat to the liberties they so deeply venerated and cherished.
It is one thing, however, to show anger at an assault on one's liberties; it is quite another to be prepared to fight for them. And in his famous speech, Patrick Henry wants to convey to his audience that the American colonists are now left with no choice but to fight for their liberties, even if it means death. Far better to die on your feet than live on your knees, as the saying goes. If the British are not prepared to give the Americans their natural rights and liberties, then the colonists must rise up in armed rebellion to ensure that they and future generations will enjoy what is rightfully theirs.
By confronting his audience with a stark choice—live in liberty or die in slavery—Henry is attempting to convey the urgency of the situation as he sees it. The time is now, and there is no longer any time to waste. The Americans must fight for their liberty.