Hi, I'm new to the Alt History forum so forgive me if I commit a faux pas, but I want to jump in and I think I have an interesting POD idea.
According to Wikipedia, one of Garibaldi's friends an American journalist, and an American diplomat schemed to make Garibaldi a major general during the Civil War. How do we get Garibaldi and Lincoln to accept the offer? How would Garibaldi's leadership affect the Union war effort? What would be the long term results (especially in regards to future American-Italian relations and Italian reunification)?
I think that Garibaldi, if decent enough, would possibly butterfly away a Grant presidency, lead to better relations between America and Italy (which might be interesting in Versailles and during Mussolini's regime), and be viewed as a second Lafayette.