What if the Poles and Lithuanians under Russian rule rose up against the Tsar during the Crimean War, and gained the support of the British and French in doing so? Could this have opened the way to an expanded Baltic Theater of the war, with British and French ships and even troops supporting the rebellion? Could the Russian defeat have been more complete, and a restored Polish Kingdom or Republic set up in the part occupied by Russia?
Or would this have drawn Prussia and Austria-Hungary into the war on Russia's side?