Entertaining as all get-out, but...no.
1) Fremont's martial law proclamation in St. Louis was Aug. 30; Polk's invasion of Kentucky was Sept. 3. Mill Springs was not until January. Fremont withdraws the proclamation or off he goes, no matter how much Jessie complains.
2) Volunteers did not get general officer commissions in 1861-62 "just because"...they got them because a) they could raise troops, or b) they had proven themselves as lower ranks: case in point, Franz Sigel, who got a full rank major generalcy (USV, not RA) in March, 1862, and because he had demonstrated his abilities as a recruiter (I fights mitt Sigel) and (somewhat) as a brigadier in 1861-62, notably at Pea Ridge. Sigel had been a US resident since 1852, as well, and he was the first emigrant to get two stars that I see on the lists...
Garibaldi, if he had come to the US, might have received a major general's (USV) commission as a volunteer, given his reputation, AND if he could actually raise any troops...if so, he might have gotten an "Latin" division, akin to Blenker's "German" division. Again, what Seward offered or alluded to in his July letter to Sandford was just that, a MG's commission in "the army of the United States" (which is an interesting choise of words), with no detail beyond that. It could have been brevet USV, actually, with a full rank BG USV. Again, there would be a quid pro quo; there always was...
As an example, it is worth noting that Charles Frederick Havelock, younger brother of Henry, distinguished record in the British army, and a MG in the Ottoman army, came to the US about the same time as a volunteer and never even got a commission, of any type. Paul Cluseret got a colonel's commission, but didn't get a BG until after Cross Keys, and that was based on his record on active service.
The other problem with Garibaldi is whatever recruits his reputation as a revolutionary may bring, his fights with the Church are not exactly going to bring Catholics into the recruiting offices...be better off offering Archbishop Hughes a commission, if that's the goal.
See the link:
http://books.google.com/books?id=ea...AT2vYC4BA&ved=0CC0Q6AEwAw#v=onepage&q&f=false
Best,
I have to agree with you here, he has far too high a rank for a foreigner. It would make it look like the US has no decent generals and has to go to Italy to get one. He would have to start off as a full col or a brigadier general at most. More likely a Lt Col. If he does an excellent job he could wind up with Grant's job at the end of the war. It would be a big uphill struggle because 1)He isn't American and 2) Grant is just that good.