[inquest]

First of all, that quote looked very much to me like a simple promise of cooperation on the part of the Senate, not an authorization for anyone to do anything. Secondly, and more importantly, it didn't delegate to the President the power to determine whom we should be at war with, and when to initiate it, as the 9/11 resolution (unconstitutionally, IMO) does.

[mrsmith]

"not an authorization for anyone to do anything"
A supportable view.
OTOH it would be hard for them to condemn any reasonable action of Washington's after the above "promise of cooperation".

Perhaps responding to Indian attacks was generally considered a matter of "repel[ing] sudden attacks" as Madison phrased the Executive's War Power at the convention. Though the irascible Senator MacClay, when informed of the failure of Hamar's 1791 army, said "A war has actually been undertaken against the Wabash Indians without any authority of Congress, and, what is worse, so far as intelligence has come to hand, we have reason to believe it is unsuccessful. Mind what comes of it. "
I suspect, after the failures of the Hamar and St Clair (sic St. Cyr) armies that Washington wanted the congress "on board" for the next campaign.