Well I think in general when your entire nation rebels and you side with the loyalists you in a uphill battle.

Just comparing the Prussian to the Swedish campaign, it seems easier to side with the rebels then the loyalists. Probably do to fact rebels spawn with a large army and your army does not.

He went with a mainly diplomatic strategy. Nothing wrong with that, but he lacked the muscle he needed to hold hungary and convince the other nations to back off. When his army starts to grow he seems to do better.

Just my thoughts.