By Germans also called the Inter-German War, the Twenty-Year War really consist of a lot of little wars, which are subsumed as the Twenty-Year War.
Since 1466, pilgrims returning from Italy had spread the news that Rome had been conquered by the infidels. Many sects believed that the end of time was near (the date of 1500 was especially often mentioned). At first the first Occidental-Seljuk War gave them hope that Rome could be reconquered, but when the Triple Monarchy of England-Castille-Portugal gave up Rome in 1472, they became desperate. Unrest started to spread. At the same time, the growing riches (and corruption) of the church (which ruled many territories in Germany) and the growing power of the princes made some people wonder about secularization of said territories.
Hell broke loose in 1475 when king Heinrich VIII secularized and annexed the bistums of Augsburg and Trient for the Luxemburger lands, the Holy Roman Empire fell into a kind of Civil War. All the princes tried to annex the clerical lands, which lead to lots of confusion. The most important of the resulting wars were the Bavarian-Austrian War for Salzburg (1485-93) and the French-Dutch War (1486-91). For some time, there were three kings in the Empire (of Luxemburg, Brandenburg and Geldern respectively).
The Swiss also used the opportunity and conquered the remaining lands of their archenemies, the Habsburgs, in the Black Forest.
Developments during the war
In the same year when the wars began, in the bisthums of Würzburg and Münster, millenialist sects took the power, declared the Gottesfreistaat (God's republic - another kind of theocracy). The latter ones even managed to extend their lands during the chaos of the war, deposing some small princes of NW Germany.
And to make the situation even worse, there were peasant uprisings (mostly in western Germany) who felt suppressed by the nobles. Those who couldn't flee to the territories of the Gottesfreistaaten where they were let in if they only swore to obey God's laws, were brutally suppressed.
The most peculiar event during the war happened in 1493: The former monk Karl Koch who had read a bit too much about the Roman republic during his time as library assistant in the monastery, started as a "soap box preacher", declared the "Rheinische Republik" (republic of the Rhine), which was soon defeated by the duke of Jülich-Berg, however.
In 1495, king Karl V of Luxemburg deposed anti-king Otto of Brandenburg, was accepted as Roman king (better said: nobody complained). Not however in Switzerland and the theocracies of Münster and Würzburg, who had stopped caring about the HRE. The wars were finally over, but Germany had lost about one fifth of its population. Only 100 years after the Twenty-Year War, the German population had completely recovered and even grown further.
Results of the war(s)
- Holstein acquired Lübeck (not the city itself; due to the complicated structure of the HRE, many cities were free cities, even though there were states around them named after them)
- Mecklenburg acquired Schwerin.
- Pomerania acquired Cammin.
- Brandenburg acquired Magdeburg.
- Thuringia only acquired Meißen and Merseburg, which is why they made war against Brandenburg, too.
- Braunschweig-Lüneburg acquired Bremen and Verden (thus gaining access to the sea), and could also acquire Hildesheim and Eichsfeld (former property of the electorate of Mainz).
- The Netherlands wanted to acquire Lüttich / Liege, but were delayed and almost beaten by Luxemburg, since they were preoccupied with the war against France, which cost them the Artois. At the same time, the French used the opportunity and took the free cities of Metz, Toul and Verdun.
- The landgravate of Hesse acquired Fulda.
- The duchy of Jülich-Berg acquired the electorate of Cologne quite peacefully.
- Luxemburg acquired the core of the electorate of Trier, including the city itself, which made the archbishop their tool. Via Tyrol they also acquired Augsburg, Bressano / Brixen and Trient.
- Nassau acquired (thanks to some smart alliances) a part of Mainz in Hesse, a part of the electorate of Trier around Koblenz, Dortmund, and the diocese-duchy of Westphalia (formerly owned by the archbishop of Cologne).
- The electorate of the Palatinates acquired Worms, Speyer and Eichstätt.
- Württemberg acquired Ellwangen, Kaufbeuren, Memmingen and Biberach.
- Bavaria acquired Freising and Passau, and after the war with Austria even the biggest chunk around, Salzburg, but had to give Eastern Styria to Austria.
- Switzerland acquired Strassburg, Konstanz and Basel.
- The republic of Venice acquired the patriarchate of Aquileia, which left the HRE.