Quick DMG to the 30 Years War

The 30 Years War was a big complicated mess, in a way that makes it uniquely gameable. It was part of what historians refer to as Europe’s General Crisis, a century-long period of violent political and religious upheaval combined with famine and plague.

It is in no way necessary for a DM to understand all the details of the 17th century political landscape in central Europe in order to run a good game in that setting (although if you happen to enjoy studying history, it certainly wouldn’t hurt), but there are a few major points that could potentially be useful to know when you're coming up with encounters, or when your players start doing things you don't expect.

So here's a quick list of simplified gameables for DMs who haven't got the time or inclination to look into the history themselves. Anyone else probably knows all this. If anyone else is you, feel free to add good stuff I left out in the comments.

• “Germany” did not yet exist as a coherent nation, and wouldn’t for a couple more centuries. Instead, the region was dominated by what was known as the Holy Roman Empire, a loosely-stitched together group of states each ruled by semi-autonomous electoral princes. By the time of the 30 Years War, many of these princes were Protestants, while the imperial dynasty was fiercely Catholic. The war was initially fought between an alliance of rebel princes and those loyal to the empire and if that doesn't sound familiar why are you even reading this?
• The violence of the General Crisis was, if not caused by, then at least enabled and encouraged by the intra-religious conflict that began a century earlier with the Protestant Reformation. The most basic way of viewing these wars, including the 30 Years War, was as a conflict between Catholics and Protestants (mainly Lutherans but Calvinism was starting to catch on too). This is the underlying conflict that a lot of that time & place’s jingoistic propaganda exploited.
• Religious oppression largely took the form of witch trials and inquisitions. Accused heretics were being executed at a faster rate than any other time in European history. So in a game with magic users, they generally would not have been trying to advertise. Bizarre wizard's towers could still exist, obviously. The setting just gives you a good opportunity to use weird magic to hide them really absurdly well.
• What began as a civil war was kept going by opportunistic and expansionist foreign nations getting involved. In 1631, when Better Than Any Man is set, King Gustavus Adolphus’ Swedish troops were sweeping through Germany. Their standard tactics were more appropriate to the technology of the time than the tactics of their rivals were, and they earned a reputation as an unstoppable horde. Each victory added territory to his relatively tiny empire.
• Aside from the continent-wide religious conflict of the day, the largest rivalry in Europe at the time was between two of its richest, most powerful families: the Bourbons in France and the Hapsburgs in both Spain and the Holy Roman Empire. Both the Hapsburgs and the Bourbons were Catholic, but the kingdom of France was squeezed between the Spanish and the Germans. This led to the Bourbons aligning themselves with the mostly-Protestant enemies of the Hapsburgs, further complicating any answer to the question “just what were these whackos fighting over, anyway?” This gives a DM multiple factions and somewhat tenuous alliances to play with.
• Soldiers were not well paid (or fed) in this time & place. It was common practice for rulers to blow their savings raising armies from a combination of foreign mercenaries and their own peasantry, then leave them to provide for themselves by “living off the land” (raping-pillaging-killing their way across the countryside). This led to a serious enmity between peasants and soldiers, regardless of sides or religious preference. There was always a wide "foraging" area around the actual armies, creating twin crises of famine and internally displaced refugees. Which made conditions ideal for the spread of the bubonic plague.
• The belief that these were the End Times was not at all unusual. The Four Horsemen of the Apocalypse (War, Famine, Pestilence, and Death) were considered by many to be the most powerful forces in Europe. This was sometimes metaphorical but often meant in a quite literal sense, especially among the uneducated peasantry, who really couldn’t be expected to grasp the bigger picture of what was happening to them. My point here is that no urban encounter table in this setting would really be complete without at least one or two doomsayers. A secondary point is that things like the physical incarnations of the Horsemen are always fun to stat up.
• This is one of those wars where the safest place to be, by far, was in the army. At least that way you had a weapon, maybe even some light armor if you’d plundered enough to afford some, and a group of other armed men that (barring extraordinary circumstances or personal grudges) had your back. The second safest place to be was in the cities and larger towns, because the worst of the pillaging happened in out of the way farms and villages. Which meant that many towns near passing armies were overrun with refugees, while others would have turned them away for fear of the plague.
• The fact that being in the army was somewhat safer than any alternative didn’t stop countless soldiers from deserting and becoming outlaws or switching sides. The punishment for desertion was hanging, but only if your own side managed to catch you, and they were usually too busy to try hunting you down. On top of that, mercenary units were often officially disbanded, penniless, armed and thousands of miles from home, putting them in basically the same position as the deserters. The major takeaway for a DM here is there were small groups of outlaws all over the damn place.
• If you don't know anything about the period at all, firearms existed but were just being introduced. They took forever to reload and malfunctions could be disastrous and they really weren't all that much more useful than swords at that point.