Declaration of War
Even with a declaration of war, most rights still shouldn't be able to be suspended - remember one of the reasons for the original war of independance from England was their taking over quarters and using private property to house their army.
There's provision for "in a manner prescribed by law" in many of the amendments, such as housing soldiers, but (for instance) much of the suppression Abraham Lincoln did was arguably blatently illegal and enormously expanded the powers of the Federal government far beyond even the most "strong government" proponent would have believed.
