Surrendering Civil Liberties in Times of War

Should U.S. citizens be forced to give up civil liberties during a time of war? Should the government have to enforce loyalty?

In the past, the U.S. has enforced loyalty by telling its citizens that they cannot say certain things about the government during a time of war. But why does it matter if it is a time of war or not? There will always be some people who oppose something, whether it is for war or for reform. When there is enough opposition against soemthing, people will unite to act against it. The cause might be war, or it might not, but the point is that the government does not take away the citizens' rights to talk against other subjects within their country.
The citizens of the U.S. should be allowed to say what they want to despite what the government thinks about how they should act at that point in time. It wouold be breaking the first amendment, the freedom of speech.