The "Thirty Years' War" was quite UN-like any other European conflict. Firstly, there was no "Germany", instead, a collection of sovereign States ranging in size from a single city to a country like Austria, forming the "Holy Roman Empire", under the authority of the Pope and an elected Emperor.
In the 16th.Century, the Reformation caused "wars of religion" between these States, until it was finally agreed that "The religion of each State shall be that of its ruler."
Then, in 1618, when the Catholic King of Bohemia died, the Protestant nobility offered the throne to the Protestant Prince Frederick of the Palatinate (Rhineland), who accepted it in defiance of the Emperor.
He was ousted by the Catholic army of the Duke of Bavaria, who then invaded the Palatinate - other States joined in on both sides, Sweden backing the Protestant cause, and Spain the Catholic one, and the war spread across Central Europe.
The armies though, were not "national", but professional "mercenary" ones, and their loyalty was to whoever paid them - and their leaders sometimes "changed sides". If they were not paid, then they took whatever they needed - and much more - from the local German populations, and in Winter, when campaigning was impossible, they settled themselves wherever they were, committing pillage, rape and murder with complete immunity, as well as spreading diseases.
The religious element steadily reduced, and the War turned into a struggle between Spain and France, Catholic France supporting the Protestant side when it was in its interest to do so. Spain was finally defeated, and France became the new "Great Power", while Prussia emerged as the most powerful German State, but "Germany" did not become a "Nation" until some 250 years later, in 1870
Read C.V.Wedgwood's "The Thirty Years' War" - quite fascinating, extremely "readable", and demonstrating Britain's enormous advantage in being an island !