Do you really want to get into the semantic discussion of the shades of meaning between "An act recognizing the existence of war" and "An Act Declaring that war exists" (Spanish American War, 1898), "war be and the same is hereby declared to exist" (War of 1812), "the state of war ... which has thus been thrust upon the United States is hereby formally declared" (WW1) and "Declaring that a state of war exists..." (WW2)?
Are you going to argue that some form of the infinitive "to declare" must be used for something to have legal or moral effect?
It would appear that some folks would be happy with spinning around three times while chanting “I break with thee, I break with thee, I break with thee!”
The Confederate government never declared war on the Union. If you disagree, please quote the declaration.