Holy Roman Empire

On Christmas Day 800 Pope Leo III placed a crown on Charlemagne in St Peter's, and a western emperor existed again for the first time in three centuries. The institution that grew from it, refounded by Otto I in 962 and lasting until Napoleon forced its dissolution, was never a state in the modern sense. Peter Wilson's history argues against reading it as a failed nation: it was a different kind of polity altogether, a hierarchy of overlapping jurisdictions in which hundreds of principalities, free cities, abbeys and prince-bishoprics held their own rights under an elected emperor.

Its founding quarrel was over who appointed bishops. Because a German bishop was also a territorial ruler with troops and revenues, the question of whether emperor or pope invested him with ring and staff was a question about who governed. Gregory VII excommunicated Henry IV in 1076, the emperor stood barefoot in the snow at Canossa in 1077 to be absolved, and the contest ran another forty five years to the Concordat of Worms in 1122, which split the ceremony: the church gave the spiritual symbols, the emperor the temporal ones.

The compromise did not settle the underlying claim, and emperors and popes went on deposing one another through the Hohenstaufen century. What it did establish was that the two authorities were genuinely distinct, a separation with no equivalent in the Byzantine east.

The Reformation happened inside the empire and could not have happened in the same way anywhere else. When Luther refused to recant at the Diet of Worms in 1521 he was condemned by the emperor and protected by his own prince, and the empire's division of authority meant that no single ruler could enforce a single religion across it. Four decades of manoeuvre and war produced the Peace of Augsburg in 1555, which recognised Lutheran and Catholic territories and left the choice to each ruler, a principle later summarised as whose realm, his religion, with a right of emigration for subjects who dissented.

Augsburg left out the Calvinists, said nothing durable about church lands already secularised, and settled nothing about the ambitions of either confession, and the arrangement broke down into the Thirty Years War of 1618 to 1648. The Peace of Westphalia rebuilt it on firmer ground: Calvinism admitted, 1624 fixed as the year by which territorial confession and church property would be judged, private worship and emigration guaranteed to dissenting subjects, and the imperial courts staffed in confessional parity.

That settlement held for a century and a half and left the confessional map of Germany much as it stands today. The empire itself was dissolved in 1806 under Napoleon, and its ecclesiastical principalities had already been secularised wholesale in 1803, ending the long European experiment of bishops who were also princes.