Papal States

The Papal States are a 1 star country that appear in the 1865 conquest as a Republic state. They are allied with: the United Kingdom, Spain, Bavaria, German Confederation, Prussia, Ottoman Empire, Romania and Bulgaria but struggle to survive very long. The Papal States hold one city, Rome, and their major threat is Italy as they surround The Papal States to the north and the south. But also they are surrounded by the Austrian Empire and France which have many units waiting to destroy you. Due to this, a conquest as the Papal States is nearly impossible.

Strategy

The only Strategy I can think of is attacking Sardina or Corsica, since they are normaly under defended and it is not possible to hold Rome for long. Since they are islands, this gives you a small defensive boost. However the Italian navy is rather strong and this is hard. Apart from using only the best generals, it is not possible to go after Italy. Once taking Corsica or Sardina, you can only hope that the United Kingdom or Spain will help as they have forces near you. If not yourdone for.

Another strategy if for some reason you don't want to brute force with wacky overpowered generals, be it Role-play, challenge or simply don't have them, is to delete the stable you start with, move the Breastplate Cavalry to directly North of Rome and build a Large Fort in its place, since that location is blocking a land route to Rome and have a clear shot over the Tyrrhenian sea. You will notice that France and Italy are both hostile on turn 1 and have massive Mediterranean navies. They will be the main instrument of your undoing if you have no answers. Next, train a Militia at Rome. Militia spam is the only way the Papal State can survive, so keep cycling them out and train more every turn. Do not hesitate to sell Industrial points or knowledge to gain the gold and train more. The enemy AI seems to target Rome exclusively and religiously, so any surviving militia from a turn should be used to body-block the remaining land route and the 2 sea tiles adjecent to Rome, though this also meant that the population cap of 25 will be an issue so a farm is recommended. For Francis II, you ideally get him as far from the attention as possible. Use him to harass Italian artilleries or even the level 2 city of Turin since he has tunnel and tactic master (which forces them to divert resource there). He starts with a Canvas Tent so it shouldn't be an issue unless you use him to engage Italian generals/admirals. You also need to be careful with your forts, their HP are incredibly valuable. Try to aim them at something that can't fire back such as transport ships, infantries, cavalries, siege artilleries, (two tiles away) or units that are close to death IF POSSIBLE. Their AoE damage will be the only thing protecting you the French and Italian navy. Once they are clear and the other powers on your side have joined, survival shouldn't be an issue anymore.

However, how are you going to make any meaningful offensives against Italy? You have no Factories (Artillery Foundries) and the city around you (Florenze and Naples) are level 5 and 4 respectively. It will take ages to break down their walls! And what if Austria sends Tegetthoff at you? There is a risky solution to this. Do everything as above, but send Francis to the sea turn 1 instead. Turn 2, you approach Corsica's shore. Hopefully this will be enough to trick the French AI into dropping one of their good generals (Preferably Napoleon III). Turn 3, run him to Savoy shores, to then land on Savoy (and maybe poke Turin) This will prompt the French army around Mets to come South to hunt for him, which pull them away from position so the German Confederation (who joins in Turn 4) can tear apart Mets' walls with their starting Howitzer and general. Then, just proceed to move around them, approach Mets, and take it once the Germans clean up whatever the French queue up to defend the city (Hopefully not a general). You also start with two spies card, so you can probably clean up the fort near Mets without an issue. With this additional income, defending Rome will be much much easier and now you also have an attack door on the French (who is also dealing with the Spanish and British and have lower city levels). Dijon starts with an Artillery Foundry so your next target should be there. If your general still have some HP (he should thanks to Canvas Tent), note that he also have Tunnel which makes it a bit easier. Note: This strategy works is luck based and work most consistently if you have training upgrades around Campaign 7-8. It should still work on lower levels of upgrade but it would be extremely harder (due to lack of mobility on the Modern Infantry unit Francis II is commanding)