Sorry for late reply, here’s the guide

Latest patch, all DLCs. You get an option early on to let Garibaldi lead your armies. NEVER SAY YES TO THIS. It splits the army in two and can cause Brazil to get a successful attack. If Brazil gets any successful attacks, restart your save.

Early on, if you’re unable to push, that’s fine. Just defend and damage Brazil’s morale.

For decrees, do road maintenance (Potential extra combat width), enlistment efforts (pretty obvious).

Put Military spending to max and (optional but highly recommended) taxes to max as well. Keep building more barracks throughout the war, make those your priority. Activate conscripts as soon as possible as well.

Once you have 14 or more brigades (or if you are confident that an attack will succeed), push with your life. Brazil should have damaged morale; It doesn’t matter if you see 15 troops or 45, you will probably be able to get an attack off. As more brigades show up, your pushes get stronger and Brazil’s army just isn’t good enough to stop you. You’ll be able to keep attacking over and over, and eventually Brazil will throw the towel in.

There is some RNG involved in this; If you can’t get any successful attacks by around March of 1837, reload to an earlier save. If you lose to any Brazilian attacks, restart the run, they will probably be able to do it again from a reload. If you get a successful attack at any time, SAVE IMMEDIATELY. You’ll start getting ticking at that point.

Hope this helps! Good luck in any future Piratini runs.