Would a DOW have passed?  No.  War was to be declared because in war the whole of the state was to be used to fight the war.  Pain was to be had by all.  Death, money, etc.  So before we were to engage in such a thing a majority of the people should be behind it.  Every member of Congress, the people's representation, should have voted to go to war.  As it stands now they left it up to the President.  The decision to go to war is not to be given to the President.  Nowhere in the Constitution is that power given as one that can be abdicated.  Congress either declares war or they do not.  You don't say to the President go if you want to.  And this one done in the case of Iraq . . . 

Not declaring war allows us to slip into war and once there it is very hard to get out . . . 10 years in Afganistan . . . example after example since our last DOW is apparent to anyone that looks at history.  The wars are longer and very few of these wars have we won . . . because when you allow the President to slip us into war . . . war is waged for every reason under the sun . . . except the one that it is meant for . . . existential threats to our country.  A vote on a Declaration of War brings focus to the question . . . do we kill and be killed?  Do we waste lives and money?  Allowing the decision to be abdicated to the President allows for obfuscation . . . oil will pay for it, in and out quick like . . . etc. etc. etc.  . . . 

The Founders were clear War brings enhanced powers of the executive, if not by design, then by default.  The decision to prosecute a war should NEVER be the Presidents.  It is like asking him if he wants the balance of power shifted more to him.  As we can see by what happened . . . wire taps, torture, etc. etc.  . . . they knew what they were talking about.