Playing an Ironman Sweden game, the year is 1592 and I'm thinking of joining the Protestant league in order to secure some strong allies for a war against Poland and Austria. Great Britain is currently the leader of the Protestants, and I'm wondering, if I join the league and declare war on Poland, a Catholic league member, will the Thirty Years' War start, or does it have to be the league leader who declares the war? I'm pretty certain I will not take over the leader role from Great Britain, since they're pretty damn strong.