Originally Posted by
Wolfgang von Zweibrücken
Is it too late to join up? A lot of countries are open...
If it's not I'd like to go Rhineland Palatinate.
I've got a pretty good idea of the main countries' army-sizes in 1618-1620 if anyone needs help. And although it's probably too late to change and a little nitpicky, Protestantism was heavily divided between moderate, "High Church" sects, like Lutheranism and Anglicanism, and radical "Low Church" Calvinist sects, like the Presbyterians, Puritans, Dutch Reformed and Huguenots.
Many Lutherans sided with the Catholics against the Calvinists (Such as Lutheran Saxony), the Czech-speaking Bohemian Brethren resented the German Speaking Calvinist court of Frederick V, and the Anglican - Puritan/Presbyterian divide was very influential in the ECW and the Scottish Wars of Religion. Some states, like Brandenburg, had Calvinist leaders and nobility with a Lutheran peasant majority, the divide between the two sides causing Brandenburg to mostly stay out of the war.
And most of the Habsburg territories, including Austria itself, were actually pretty Protestant at the start of the war - possibly majority Lutheran, with a very small number of Calvinists, but the ruling class were almost all Catholics.
Bohemia and Moravia (modern day Czech Republic and Slovakia) were majority protestant - maybe 25% Lutheran, 40% Bohemian Brotherhood, and 30% Catholic, with a small Calvinist minority. Most Imperial Officials were Catholic, most Urban German-Speakers were Lutheran and most peasants and farming nobility were Bohemian/Moravian Brotherhood.
In the opening days of the war Austria was invaded by an Army of mixed Protestant Bohemians, Moravians and Germans, in the service of the Rhineland under Mansfeld, Thurn and Schlick from the North, Calvinist Transylvanians and Hungarians from the east, and an army of Lutheran Austrian rebels attacking from the south. It was only due to the divided nature of this multi-national force that the Habsburgs survived, that and the intervention of Bavaria.
My suggestion would be:
England: 60% High Church Protestant (Anglican), 35% Calvinist (Puritan), 5% Catholic
Scotland: 60% Calvinist (Presbyterian), 10% HC Protestant (Anglican), 30% Catholic
France: 75% Catholic, 25% Calvinist (Huguenot)
Rhineland: 90% Calvinist (Heidelberg Confession), 5% HC Protestant (Lutheran), 5% Catholic
Brandenburg: 75% HC Protestant (Lutheran), 20% Calvinist (Heidelberg Confession), 5% Catholic
Bavaria: 90% Catholic, 10% HC Protestant (Lutheran)
Brunswick-Luneburg: 85% HC Protestant (Lutheran), 10% Calvinist (Heidelberg), 5% Catholic
Austrian Habsburgs: 40% Catholic, 50% HC Protestant (Lutheran/Bohemian Brethren), 10% Calvinist
Netherlands: 80% Calvinist (Dutch Reformed, Arminian, Puritan, Huguenot, etc.), 15% HC Protestant (Lutheran), 5% Catholic
Denmark-Norway: 90% HC Protestant (Lutheran), 10% Calvinist
Sweden: 90% HC Protestant (Lutheran), 10% Calvinist
Saxony: 75% HC Protestant (Lutheran), 10% Calvinist, 15% Catholic
I don't blame you if you find that too complicated. The Austrian situation is pretty important though - the popularity of Protestantism in Austria and the Habsburg lands was a major cause of the war.
Also, Prussia and Brandenburg were ruled by the same guy - the Elector of Brandenburg. This was more direct than even the Scotland/England issue - there was no independent action on the part of Prussia.