The problem is, if one believes that something is necessary to save the country and the Constitution, one tends not to see it as unconstitutional.
After years of war, our Founders well understood, and provided in the Constitution for restrictions on normal freedoms during times of "insurrections," "rebellion or invasion".
Indeed their Alien and Sedition Acts of 1798 were originally passed in preparation for war with France -- now called the "Quazi-War".
And in the very beginning, those acts were not opposed by Jefferson & Madison's political party, though as the possibility of major war faded, their opposition became very strong, and the nation nearly succumbed.
President Jefferson himself used the acts to prosecute political opponents.
So I'll say it again: this is one reason Congress has been so reluctant to officially declare a war these past 70+ years -- because of all the historical precedents it would invoke.
And that is especially true when the real "war" is considered to be just as much ideological as military -- in the war between freedom and tyranny we considered ourselves "defeated" to the degree that we must adopt tyranny just to suppress our enemies.
But the bottom line is still: our Founders and every generation since have well understood that wartime requires sacrifices in terms of both lives and freedoms.
It's one reason why they hated war.