The Kingdom of the Two Sicilies starts out in a fairly advantageous position for the eventual unification of Italy. Historically a rebellious Sicilian population and, perhaps more so, inept monarchs crippled the Two Sicilies. Without these problems the Two Sicilies can beat out Sardinia-Piedmont for dominance over Italy.
The Two Sicilies begins with four regiments and a large fleet. The advantage of the fleet is transport; moving over land is slow, but you can use your fleet to drop off your men where you want them in far less time. Still, starting out you won’t be battling any other navies, so cut the naval budget. Keep the defense budget where it begins (at 50%) and leave army maintenance on full. Then raise taxes (60% for the peasantry and 49% for the others) and put crime fighting to minimum.
Crime will become a problem but not for the first few years, and right now you need the money. Put education on full. You don’t have any machine parts, so you need to follow the research paths that will give you some. If you can’t go for an industrial tech that will lead to machine parts, go for military technologies. Ignore naval techs completely. Raise tariffs to 70-75%. Don’t raise them all the way – if you do, your people won’t be able to afford all their goods. That not only makes them surly and restless, but they won’t be paying tariffs on the goods they aren’t buying. Lower tariffs will actually make more money.
The military-industrial complex
The Two Sicilies begins with three factories: Ammunition, Small Arms, and Glass. You will need to buy coal, iron, and steel. You also want to set to buy ships (only about 5) and machine parts (you don’t have the prestige to get any yet but you will). Also set to buy at least 50 canned goods. Since you make small arms, you have the opportunity to raise your mobilization pool. You can add 5 to your mobilization pool immediately, and ought to do so. It’s always good to have a reserve.
Unification: the Risorgimento
Now it is time to begin the unification of Italy under Southern Italian leadership. Look over the treaties of the Italian States. Sardinia-Piedmont, Lucca, Tuscany and the Papal States are all linked not only to each other but also to France and probably Spain. You don’t want to get on France’s bad side. If necessary you can maintain the favor of France and/or Spain by selling them technology. As long as they are pacified they will keep defensive alliances with you (Spain might even go for a full alliance). That will keep Sardinia-Piedmont off your back. Now look at Modena and Parma. They are allied to each other and the Papal States, but not to any great powers, nor to you. They are also small. You are going to declare war on Modena, but not just yet. First load up all your infantry units onto your navy (leave your cavalry in Naples) and sail them to the Papal States lands in the northeast of Italy. You are allied with the Pope so you can land the men and position them on Modena’s border. It’s a longer march but you won’t need to risk the penalty of fighting an opposed naval landing.
Once your men are in position, declare war. The Papal States will almost certainly join the war against you. Move your cavalry from Naples directly onto Rome. Once you defeat the infantry holding the city, occupy it. Move your infantry into Modena. Do not occupy the Papal States’ land in the northeast first. It is more important to hold Modena and Rome, the capitals of those two states. Move your navy back to the west coast. Once you occupy Rome you can pursue the Papal infantry into Ancona or wherever and occupy that territory. You can also use your navy to move the cavalry up into Modena if your troops need support.
After Rome is occupied, the Pope will start to offer terms. Wait until you also occupy Modena and the Papal States will offer you a deal – large chunks of central Italy and some prestige. Take it. You can cut the Papal States in half and probably gain a factory. The Papal States are full of Southern Italians too.
Meanwhile you should move your troops south from Modena and take Massa. The enemy may try to reoccupy Modena once you’ve left. If so that’s a bonus. You have more men, you can occupy Massa faster than they can take back Modena. Occupy Massa and then either satellite or annex Modena. Annexing will gain you a canned goods factory. Creating a satellite will gain you a buffer state you can annex at your leisure and keep down the number of BadBoy points (the last thing you want is a badboy war). Either way you gain Massa. Now move onto Parma and annex that. Two down, four to go. Now you have some domestic iron production, and just in time. The world market will begin to run dry. You also have some prestige and should have some technologies, so you can get machine parts and build some factories. Building a Fabric factory and then a Regular Clothes factory will make a hefty profit (cotton is dirt cheap, and clothes sell for a nice price). A Steel mill will also prove useful for when the world market runs short on that commodity.
Time to wait. Build up a technological base, increase your mobilization pool, and keep on the good side of France and Spain. If you have some excess money, why not found a colony? Yebuti (next to Somaliland) can be colonized with just a single trading post. It’s a good way for a small state to build up a bit of prestige. A war with Egypt might also prove useful, particularly if Egypt just lost a war, but make sure France didn’t guarantee their independence. If you are in the clear, try and gain Crete and Cyprus. They have a nice labor pool that just needs to be educated to work in factories, or they can be mobilized to your benefit. Excess territories can be sold to France.
The second unification war
Eventually you will be told your treaties expired. That’s what you’ve been waiting for. Everyone else’s will have expired too. Act fast, before they can either reform them or get guaranteed by France. Do take the time to re-establish your own defensive treaties with France and Spain. If nothing else it will keep Austria from jumping you.
Now hit Lucca. It’s an easy annexation. If the Pope joins in, mobilize and reoccupy Rome. Put your mobilization pool to good use. He’ll cry uncle and pay you off in land. Once you have Lucca, mobilize and move on Tuscany. If you fought the Papal States you may need to wait a bit to reinforce. If Tuscany allies with anybody (except the Pope, whom you know you can defeat) just wait it out. Then annex them. One reason it’s an advantage to wait is that you will lose badboy points over time. With care you will never have more than five at once and the other Great Powers won’t see you as a threat.
Sicily: a great power
“Other” great powers because the Two Sicilies should be one by now, even if it’s a low number seven or eight. Keep building industries, raising troops and founding colonies when affordable and you can keep that status. You’ll lose it during wars, but regain it once you triumph. Attack and annex the Papal States, Modena, and Tuscany if you haven’t already. Now it’s just you and Piedmont. Sardinia-Piedmont tends to be allied with and guaranteed by France, but you can wait that out. Or not – you’re a major power now, and you just need to control Turin, not own it, to form Italy. You’ve already got the other territories (Rome, Modena, Parma, Florence, and of course Naples).
The next path is up to you. Carving up more of Egypt may be easiest. Carry out a two-step annexation to minimize badboy gain, remembering to humiliate them properly to minimize the prestige loss of the second war. If other North African uncivilized countries like Tunis or Tripoli can be annexed at little prestige cost, go for it too. Putting your colonial population into uniform allows you to convert more of your state culture POPs into craftsmen and clerks, furthering your industrialization. Reform the Roman Empire!
France and Spain can be trusted allies when approached with due care. Austria may prove vulnerable when they’re mixing it up with Prussia or Russia or the Ottomans (or all three).
In conclusion, industrialization and opportunistic expansion while staying in the good books of as many Great Powers as possible are the keys to opening the gate to a unified Italian Great Power.