holy alliance

In the lead-up to the Crimean War, Nicholas I of Russia expected Franz Joseph I of Austria to not interfere against him, and possibly even join him. This was partly because they were both members of the Holy Alliance, and partly because Russia had earlier helped Austria to put down the Hungarian...

Let's say Napoleon III is less religiously Imperial and doesn't intervene in the Crimean War and the Protection of the Papacy. So Sardinia does not join. And the Russian ally, Austria who Russia supported less than a decade back in the Hungarian Revolution of 1848 possibly joins or stays...