On the twenty third of May 1618 a group of Bohemian Protestant nobles went to the royal castle in Prague, held a brief trial of two imperial governors, and threw them out of a window some twenty metres above the ground, along with their secretary.
All three survived. Catholic accounts credited angels; Protestant accounts credited a dung heap. The detail is worth keeping because it is the last comic thing in the chapter.
The grievance was constitutional. Bohemia was an elective kingdom whose nobility had obtained written guarantees of religious freedom, and the new Habsburg king was closing Protestant churches on the argument that the guarantees did not cover land held from the church. The defenestration was a formal act of defiance in a legal dispute, done in a traditionally Bohemian way; the same castle had seen a similar event two centuries earlier.
The estates then deposed him and elected a Calvinist prince from the Rhineland instead. That is the point at which a Bohemian quarrel became a European one, because the man they deposed was about to be elected Holy Roman Emperor, and the man they elected was one of the seven electors who would choose him.
The settlement of 1555, described at the end of chapter twenty five, had three holes in it, and all three were now load bearing.
It recognised Catholics and Lutherans and not Calvinists, who by 1618 held several important territories including the Palatinate. Legally they had no standing at all.
It provided that church lands secularised before 1552 stayed secularised, and that any bishop or abbot converting afterwards must resign his lands. In practice a great deal of church property had been taken after the deadline and the clause had not been enforced. Every one of those estates was a lawsuit waiting for a court willing to hear it.
And it made each prince the arbiter of religion in his own territory, which meant that the empire's constitutional machinery, its diet, its courts and its circles, was now divided along confessional lines and increasingly unable to decide anything. By 1608 the imperial supreme court had effectively stopped functioning because the two sides would not accept its judgements.
Add the underlying constitutional question, which was whether the emperor was the head of a monarchy or the elected president of a federation of sovereign princes, and Bohemia was the spark rather than the cause.
It is easiest to follow as a sequence of interventions, each by a larger outside power responding to the previous one's success.
The Bohemian phase ended fast. The new king was defeated outside Prague in 1620 at the White Mountain, lost his own lands as well, and the Habsburgs used the victory to break the Bohemian nobility completely: twenty seven leaders executed in the Prague square, more than half the land in the kingdom confiscated and redistributed, and Protestantism suppressed. Bohemia's recatholicisation was thorough and permanent.
The Danish phase followed, when the Lutheran king of Denmark intervened to protect north German Protestantism and his own interests. He was beaten. In 1629 the emperor, at the height of his power, issued an edict ordering the restoration of all church lands taken since 1552. Enforcing a legal claim that had lain dormant for seventy seven years terrified every Protestant prince and alarmed the Catholic ones, who did not want an emperor strong enough to do such things.
The Swedish phase changed the war. Gustavus Adolphus landed in 1630 with a well drilled army, lighter artillery and a tactical system of shallower formations combining musket and pike, funded partly by French subsidies. He destroyed an imperial army at Breitenfeld in 1631, marched into southern Germany, and was killed at Lützen in 1632, after which Sweden fought on for sixteen more years without him.
Then France entered openly in 1635, on the Protestant side, under a cardinal. That is the fact that settles the question of what the war had become. Catholic France funded and then joined a coalition of Protestant states against Catholic Habsburgs, because the strategic problem was Habsburg encirclement and had been for a century. The last thirteen years were a straightforward struggle between France and Spain and Austria, fought largely on German soil.
The mechanism that turned a war into a demographic catastrophe was the way armies were raised and fed.
Nobody could afford a war of this length out of taxation. So states contracted with military entrepreneurs, who raised regiments on their own credit and were repaid out of the war. The most spectacular, Wallenstein, raised armies of tens of thousands for the emperor on the explicit understanding that they would support themselves from the territories they occupied, and he became one of the richest men in Europe before being murdered on the emperor's orders in 1634.
The system was called contributions, and it was a formalised extortion: an army would assess a district for a monthly sum in money and supplies, and collect it. A district that paid was ruined slowly. A district that could not pay was plundered.
Armies moved with enormous trains of dependants, wives, children, servants and traders, often outnumbering the soldiers, all of whom had to eat. They spread typhus, dysentery and plague as they went, and they concentrated populations of refugees in walled towns where epidemics did the rest.
The battle deaths across thirty years were a small fraction of the total. People died of hunger after the fourth requisition, of typhus in a crowded town, of plague, and of the collapse of the agricultural cycle when the seed grain and the plough animals had gone.
Discipline was not absent, and that is what makes the system rather than the men the explanation. Armies had articles of war, provost marshals and gallows, and commanders hanged plunderers when they wanted order kept. But an unpaid army cannot be forbidden to feed itself, and pay was chronically months or years behind. Mutiny over arrears was routine, and several campaigns stopped dead because the troops refused to move until they were paid. The sack of a town taken by storm was, by the convention of the age, the soldiers' legal entitlement, which is a rule that makes sense only if you assume the town will be somebody else's.
The event that fixed the war in memory was the storming of Magdeburg in 1631. The city of around twenty five thousand was taken, sacked and burned, and perhaps twenty thousand died. It generated an enormous pamphlet literature across Europe, and the verb to magdeburgise entered German for a while.
The written record from below is thinner than for the twentieth century and it is not absent, and it is worth using.
A cobbler in Swabia kept a chronicle through the whole war. A Bavarian peasant, a Protestant minister in the Palatinate, an abbess, several town clerks and a mercenary soldier all left accounts. What they describe is not battles but repetition: soldiers arriving, demanding, taking, leaving; then a different set arriving.
The recurring detail is the flight to the woods. Villagers learned to watch the roads, bury or hide their grain, drive the animals into the forest and go with them, and wait. Some communities did this dozens of times over three decades. The soldiers learned this too, and torture to reveal hidden stores became routine enough that the sources have standard names for the methods.
The other recurring detail is the collapse of the ordinary machinery of life. Fields unsown because the seed was taken or the season missed. Mills burnt, so grain that survived could not be ground. Parish registers with gaps of years where nobody was there to write in them, then resuming in a different hand. Wolves reported in districts that had not seen them for generations, which is a reliable indicator of abandoned land.
And the moral disintegration that follows, which the diarists record with more shock than they record the violence. Neighbours informing on where a neighbour's cattle were hidden in order to save their own. Refugees turned away from towns that could not feed them. Children abandoned. These are the entries the writers return to years later.
The population of the German lands fell by something in the region of a fifth to a third overall, with enormous regional variation. Some territories in the path of repeated campaigns lost half their people or more; Hamburg and the north west were barely touched.
These figures are not guesses in the way that medieval ones are. German territories kept hearth and tax registers, and historical demographers have reconstructed local populations from parish registers of baptisms, marriages and burials. The picture is of villages that lost most of their inhabitants and were resettled by immigrants over the following two generations, and of some that were never reoccupied.
Beyond the deaths, the destruction of capital: herds, mills, bridges, seed, and the accumulated credit relationships of a commercial economy. Regions that had been among the wealthiest in Europe in 1600 took a century to recover, and some historians date the long divergence between north western Europe and central Europe to this period, though that argument is contested.
There was one further cost that is easy to miss. The witch trials of central Europe reached their peak in exactly these decades and in exactly the regions worst hit, and the correlation with crop failure, epidemic and war has been examined statistically and holds up. Communities under unbearable pressure looked for someone inside them to blame, and the courts obliged.
And a political result. The empire emerged as a confederation of effectively sovereign states, which is the subject of the next chapter, and Germany's fragmentation was locked in for another two centuries.
Firm: the campaigns, treaties and diplomacy, documented exhaustively by every participant. Also firm, unusually, the demography, thanks to parish registers.
Soft: the mortality totals. Overall figures of four to eight million circulate; they are aggregations of local studies extrapolated to unstudied regions, and the upper end depends on assumptions about the worst affected areas.
Soft: Magdeburg. The death toll comes from contemporary reports written for propaganda purposes on both sides, and the cause of the fire that destroyed the city was disputed immediately and remains so.
Contested: whether it was a religious war. It began as one and ended as a struggle between dynasties, with the most Catholic power in Europe funding the Protestant side. The most useful description is probably that religion determined who could ally with whom at the start, and that by the 1640s it determined almost nothing.
Contested: the German trauma. The idea that the war left a permanent scar on German consciousness was constructed largely in the nineteenth century, by writers who wanted an explanation for German disunity and a grievance against France. The suffering was real. The continuous three hundred year memory of it is partly a later invention, and the single most vivid source most people know, a picaresque novel published in 1668, is fiction written by a veteran and should be read as such.