France helped the US to win the ARW against Great Britain - but when the revolutionary and republican France fought a decisive war against the same enemey, the United States did nothing to support their former ally. We have to change this.
What if an American Legion, consisting either of radical citizens privately hired, or of professional soldiers sent to France as an expeditionary corps, fought in Europe against Britain and its allies (mainly Austria, Prussia and Russia) during the French Revolution, the Consulate and/or the First French Empire?
How could such a unit be formed? Where could they fight? How would they do against European infantry? Would such a unit harm British-American relations on the long term? And how would an American Legion influence 19th century politics and military tactics in France and America?