I was wondering if (for whatever reason) the Civil War is avoided, does the United States get involved in a war against a different opponent during that same time period, the 1860's to maybe the 1880's? I don't include the wars against the Native American tribes of the Plains because that conflict had already been going on when the Civil War began.
The only one I can really think of for this time period is fighting against France during their intervention in Mexico.
Thoughts? Ideas?