I used to pride myself on the list of congressional authorizations of military force [AUMF] that I included in Congress at War. What was and remains significant is that lawmakers have voted military action many more times than the five conflicts in which they specifically declared war.
Then, reading by chance a history of the Madison administration, I discovered that Congress had authorized -- in secret in 1811 -- a war in Florida. So my list was incomplete.
And now, reading a book on U.S. foreign policy before the Civil War, I saw reference to a congressional action in 1839 authorizing the President to "resist any attempt" by Britain to enforce jurisdiction over disputed parts of Maine, to call forth the militia, to accept up to 50,000 volunteers. It even appropriated $10 million to carry out the act. [U.S. Statutes III, chap. LXXXIX, March 3, 1839.] As things turned out, of course, there was no war. I guess that's why this law never made the lists I mentioned earlier, or the extensive list in a paper by the National Security Network.
The lesson for me: there's always more to learn from history.