Explanation: There was something of an ideological divide in expat/immigrant Italians fighting in the US Civil War - many of those fighting for the Union were veterans of the forces of the great liberal revolutionary Giuseppe Garibaldi - and many fighting for the Confederacy were veterans of the Bourbon monarchy of Two Sicilies which Garibaldi played a part in defeating. LET’S GO SONS OF GARIBALDI

https://en.wikipedia.org/wiki/Italian_Americans_in_the_Civil_War

The last two lines are a nice touch