In an age of liberal democracy, it is easy to forget that for most of human history, the world has been dominated by dynastic monarchs – by men (and, less frequently, women) who owed their position to their bloodlines. And no period of European history is more closely associated with dynastic rule than the Middle Ages.

The very way we think about dynasty is conditioned by the Middle Ages. It was in this era that the family tree, beloved of amateur and professional historians alike, was invented. It was also in these years that heraldry developed, a tradition kept alive proudly (if eccentrically) by the College of Arms. These are not the only legacies. The political map of modern Europe owes much to the vagaries of medieval dynastic fortune. It was only the chance death of Lothar II – who gave his name to Lorraine – without heirs that denied Europe a sprawling ‘Middle Kingdom’ between France and Germany. Likewise, it was the union of the ruling families of Castile-León and Aragon in 1469 which ensured that most of Iberia would in the future form a single Spanish realm. Just as fascinating are the roads not travelled. When Charles IV of France died in 1328 without a male heir, one of the strongest claimants to the throne was Edward III of England. In an alternative universe, Boris Johnson might be presiding over a Paris-based parliament, extolling the virtues of la patrie.

To understand medieval politics, we must therefore understand the dynamics of dynasty. Robert Bartlett takes us a considerable step closer to doing so in this masterful survey in which he traces the complexities of royal familial politics. His canvas is wide, taking in all the dynasties of medieval Europe (including