The House of Habsburg has a plausible claim to having been the most successful ruling dynasty in world history. For a thousand years, from the dynasty’s emergence as feudal warlords in northern Switzerland in the 10th century to their ousting as emperors of Austria in the early 20th, they reigned at one time or another in most European countries (including, briefly, England and Ireland), and over colonial possessions that reached across the globe, from Peru to the Philippines (the one nation that still bears the name of a Habsburg king).

Their legacy is tenacious. Throughout Europe, it lingers in the placement of borders, in patterns of confessional belief, in styles of architecture, even in ideas of national and supranational sovereignty, the second of which the English common law mind finds so baffling and strange. That bafflement has consequences. Without a knowledge of the Habsburgs and the dynastic union they created, many aspects of contemporary Europe are unfathomable. But in an age when most British historians are monoglot and their researches are monothematic and ever-narrower in chronological range, it is a deficiency that few can even attempt to make good.

All of which means that Martyn Rady is something of a rarity. Based at University College London, he is a polyglot historian of almost encyclopedic breadth, and his learning is as all-encompassing as it is lightly worn. In his new book, The Habsburgs, he has produced a Rolls-Royce of a narrative that motors through ten centuries of history with an effortlessness that belies the intellectual horsepower beneath the bonnet.

There are some explanatory potholes to be negotiated along the way. One is the anachronism of the moniker ‘Habsburg’ itself. True, an early forebear, one Radbot (985–1045), built a fort on a southern tributary of the Rhine and named it the Hawk’s Castle – Habichtsburg in Old High German, gradually contracted to Habsburg. But once the family began to acquire more glamorous titles, the one used by its early members, count of Habsburg, soon slipped from view. It took the 19th-century Gothic Revival and the interest it reawakened in all things medieval to bring the name back into common use.

For most of the dynasty’s existence, it was known almost universally as the House of Austria, a designation that the innocent British reader might assume refers straightforwardly to a place. But it is rather more complicated, as Rady explains: ‘Austria was not really a land at all, but a learned construction that brought together the themes of empire, mission, inheritance, and destiny … it signalled a set of beliefs about the ruling house that stood apart from geography.’ Thus when members of the dynasty went on to rule in Burgundy and Spain, they continued to refer to themselves as members of the House of Austria, even though their physical connection with the place was next to nonexistent. Austria, for these purposes, was ‘as much an idea as a space’. By the end of the 16th century, that supranational ‘idea of Austria’ was sustaining a system of rule that extended from the Balkans to the shores of the Pacific.

Indeed, the original Habichtsburg was not even in Austria, but far to the west, among the rustic cowherds of northern Switzerland. It was this region’s wealth that sustained the dynasty’s steady rise to political prominence within the medieval Holy Roman Empire (the union of states, with its elected emperor, encompassing most of central Europe, from northern Italy to the Baltic). By the 1270s, Rudolf of Habsburg had secured election as king of the Romans (or emperor-elect). During the next century the dynasty moved east, conquering Austria, making it their territorial powerbase and turning Vienna’s old fort into their principal residence (the core of the present-day Hofburg).

This vertiginous rise owed as much to the dynasty’s marriage-making brains as it did to its military brawn. ‘While others wage war’, ran a contemporary Latin quip, ‘you Happy Austria, get married.’ Carefully chosen brides and a rabbit-like capacity for reproduction kept the House of Austria going while other more illustrious rivals petered out. Time and again, as these became extinct in the male line (the Valois dukes of Burgundy in 1477, the Trastámara kings of Castile and Aragon in 1504, the Tudor kings of England in 1553), the House of Austria produced yet another large-chinned son, ready to take a lonely heiress and her territories into the Habsburgs’ protective embrace.

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The dynasty’s prestige expanded in tandem with its property portfolio. By the end of the 15th century, the once-elective office of Holy Roman Emperor had become de facto hereditary within the House of Austria. But the real masterstroke was the marriage of Philip, eldest son of Emperor Maximilian I, to Infanta Juana, heir to the Spanish kingdoms, in 1496. The result was that their eldest son, the Emperor Charles V, became the ruler of lands that encompassed not only most of continental Europe but also unimaginably large territories in the New World – the first empire on which ‘the sun never set’. In distant Mexico, Charles’s Aztec subjects hailed him as ‘Lord of Earthquakes’, crediting him with the power to command the ‘giant subterranean armadillos, whose burrowing caused the earth to move’.

Possession of so gargantuan a patrimony came with giant-armadillo-sized challenges: in the 16th century, these were the seismic shock of the Reformation and the religious wars that followed; in the 18th, the threat posed by Frederick the Great’s expansionist Prussia and, later, by revolutionary France; and then in the 19th, Napoleon, with his ambition to replace the ancient Holy Roman Empire (dissolved in 1806) with a new European empire of his own. That’s not to mention the perennial problem of ‘the Turk’: the Ottoman sultans, whose forces twice besieged Vienna (in 1529 and 1683) and for most of the 16th and 17th centuries threatened to carry the crescent banner onwards to the Rhine. It’s little wonder that Charles V when he abdicated, exhausted, in 1556 divided his inheritance between his son in Madrid and his brother in Vienna in an attempt to make government more manageable.

Yet a far more potent threat to the dynasty’s survival than Luther, Napoleon or the Ottomans came from its genes. Generations of marriages between first cousins or between nieces and uncles eventually resulted in physical deformities (including that exaggeratedly large ‘Habsburg jaw’) and instances of epilepsy and mental illness. Consanguinity also killed. Among the thirty-four children born to the Spanish Habsburg royal line between 1527 and 1661, there was ‘an infant mortality rate of 80 per cent’, or four times the average in the period. By 1700, for all the dynasty’s capacity to reproduce, the Spanish Habsburg line was extinct. The Austrian line ran out of male heirs forty years later, and was only saved by the unprecedented admission to the imperial throne of a female heir in the person of Maria Theresa. Her prodigious fecundity ensured a steady supply of emperors into the 20th century (albeit of the now hyphenated House of Habsburg-Lorraine).

In less able hands, a narrative canvas as broad as this would sag and unravel. Not so here. Themes and contexts are crisply delineated. Major developments – in the spheres of culture and ideas, economy and society, diplomacy and war – are seamlessly introduced. And the vast cast of characters is depicted with a mix of insight, sympathy and astringent Gibbonian wit that makes them instantly memorable: figures such as the consort of the Emperor Frederick III, ‘who was renowned both for her beauty and for her ability to drive nails into oak planks with her bare fists’; or King Philip III, who ‘like Shakespeare’ thought land-locked Bohemia had a coast and when it revolted wanted to send the Spanish navy to suppress it; or the reformist Joseph II, who ‘governed in the same way he had sex – energetically and with such unrestraint that he looked forward to periods of abstemiousness in the countryside’; or the dullard Francis II, in thrall to his chief minister, Metternich (‘never less than duplicitous’), who devoted his time to ‘making bird cages, lacquer boxes, and toffee’.

Habsburg government was rarely less than authoritarian and there were undoubtedly moments of bloody repression, as when Philip II burned alive Protestant heretics in the macabre theatre of the auto-da-fé, or when Franz Joseph’s army killed Italian ‘patriots’ in their thousands during the brutal suppression of the 1848 revolts (the field marshal responsible is still celebrated in Vienna every New Year’s Day in the jovial clapping and foot-stamping that accompanies Johann Strauss senior’s Radetzky March). For the most part, however, the regime proved adept at presenting this authoritarianism as wisely paternalistic and instilling a sense of personal loyalty to a beneficent and divinely appointed monarch that transcended the empire’s multiple affinities of language, nation and place. As an ideology of rule, Rady argues, it proved highly resilient, notwithstanding the rise of nationalist movements in the 19th century – even after, and in some ways because of, the nationalist-inspired assassination of the heir apparent at Sarajevo in 1914.

Part of that resilience came from the skill with which the Habsburg monarchy coopted potentially subversive ideas and appropriated them to the service of the state. The ideals of the 18th-century Enlightenment, generally so hostile to absolute monarchical rule and the Baroque rhetoric of ‘throne and altar’ that sustained it, provide a case in point. In Britain and North America, writes Rady, ‘the Enlightenment tended towards the extension of popular sovereignty, curbs on government, and … individual liberty and the rights of the citizen’. In the Habsburg world, by contrast, it conduced ‘towards regulation, the “science of the state” … and the subjection of the individual to the common good, as the sovereign understood it to be’. Among the Habsburg bureaucracy, this outlook fostered a sense of their own ‘superiority as a governing elite and brotherhood of intelligence’, which gave them a powerful belief in their entitlement to rule.

In modern-day Brussels, once the most opulent of all the Habsburg capitals, those divergent Enlightenment traditions still confront each other in a state of mutual incomprehension. It is not the least of Martyn Rady’s achievements that his book sheds light on the present almost as brightly as it illuminates the past.