If by magic you could place your finger on a defining moment in time, you could do worse than to place it on Paris in 1919. There, at the close of World War I, the Great Powers created a “new Europe” that in 20 years would proceed “to tear itself to shreds.” The Powers drove several nails into the coffin of the Ottoman Empire, carving up the Middle East in ways that haunt us still. The ghosts of Alexander the Great’s empire lived on in the ambitions of Greece’s dynamic prime minister, Eleutherios Venizelos, hell-bent on possessing Constantinople once again. In 1922, the League of Nations approved new Hashemite kingdoms and drew the borders of catastrophes to come. If our world now seems a mess, you should be able to feel it building at your fingertips.

This is the point at which John Julius Norwich concludes his massive and highly engaging history, “The Middle Sea: A History of the Mediterranean” (Doubleday, 610 pages, $39.95), ending on a note of characteristic elegance and not a little sadness:

Some six or seven thousand years ago the Mediterranean gave birth to Western civilization as we know it. Its relatively small size, its confined shape, the gentleness of its climate, its blessed fertility and manifold indentations of its European and Asiatic shores, all combined to provide a uniquely protective environment in which its various peoples could develop and flourish.

Though he claims no scholarly credentials, Mr. Norwich has demonstrated his familiarity with these peoples in three magisterial volumes on the Byzantine Empire and one on Venice. An English aristocrat who had the good sense to fall in love with sunnier climes, Mr. Norwich is intimately acquainted with the region.

His task, of course, is impossible — to achieve in one teeming volume what whole libraries cannot do. He tells us at the outset he will be “mercilessly selective”in his account. What saves him and us is a genuine storyteller’s determination not to bore. You can see this straightaway when, racing through an account of Egypt’s pharaohs, he pauses at the bust of Nefertiti, which “suggests that she was one of the most ravishingly beautiful women who ever lived.” A mischievous footnote adds, “Though I wish someone would do something about her left eye.”

It’s in the footnotes and humorous asides, the dilations on personalities and eccentricities, that Mr. Norwich’s history most excites. I can’t help loving this footnote to a tour of the Parthenon: ” … the architect Harry Goodhart-Rendel, seeing it after the Second World War for the first time, remarked to Osbert Lancaster, ‘Well, I don’t think we can call it a complete success.'”

Mr. Norwich lets you know he’s been there and can describe all the ruins first hand. His pages thrive with arcana, like the fact that Spain’s Pamplona is named for the Roman Pompey, or that Caligula, “not content with incest with one of his sisters, regularly offered the other two ‘to be abused by his own stale catamites,'” or “that the Emperor Septimius Severus, expiring at York in 211, was the last Roman Emperor for eighty years to die in his bed.”

With Constantine the Great, we have the toleration of Christianity, the beginning of the end of the classical pagan world, and the foundation of one of the world’s great cities, which Turks would pronounce Istanbul. Byzantine history is Byzantine in every sense of the word, and more than one historian has managed to make it dull. Not Mr. Norwich. The wars with Goths, Huns, Ostrogoths, and Visigoths are so prolix that one imagines enterprising novelists could glean whole trilogies from each of Mr. Norwich’s paragraphs. As for Rome’s fate at the hands of the Christian barbarian, Alaric, Mr. Norwich observes, “A sack, nevertheless, remains a sack …” The decline of the Western empire and the ascendancy of the East are all well told with their popes and patriarchs, generals (at least one a successful eunuch) and emperors, the growing threat of Islam in Spain and the Levant, the strange phenomenon of the Holy Roman Empire with its movable (and removable) crown.

We have the “papal pornocracy” of the 10th century and, most disturbing of all, the bloody and chastening tale of the Crusades: ” … amid scenes of hideous carnage, the soldiers of Christ battled their way into Jerusalem, where they celebrated their victory by slaughtering all the Muslims in the city and burning all the Jews alive in the main synagogue.” Some of this tale, in which a merciful Saladin spares the Christians of the Second Crusade, is now questioned by revisionists — one can readily see how medieval history lends ammunition to all sides in current debates about the war on terror. However this story plays out in the future, Norwich has retold it with gusto and sympathy.

The Fourth Crusade, in which Catholics skipped Jerusalem and sacked Orthodox Constantinople instead, only adds to the “diabolically complicated” history of the Greeks, one of a handful of peoples Mr. Norwich follows with greatest attention. When he gets to that fateful Tuesday in 1453, when Mehmet II defeated Constantine Paleologos and took the city for the Ottomans, his cinematic crosscutting builds suspense until the last Mass at Hagia Sophia: “The officiating priests continued with the Mass for as long as possible before being slaughtered where they stood, at the high altar … ” Mehmet II was no merciful Saladin, but at least he did not destroy the great church. One hundred years later Süleyman the Magnificent, with his brilliant architect Sinan, erected the twin edifice of the Blue Mosque, so that monuments to both Christianity and Islam could stare each other down through the ages.

The Ottoman Empire, which would eventually succumb to its own corruption, overreaching, and bad alliances, was not the worst ever to dominate the Mediterranean. Though Mr. Norwich is right to express relief that Islam did not conquer Europe, Christian civilization provided enough intolerance to go around. Expelled from Spain, Jews settled among the Ottomans in Salonica and Istanbul, where multiple faiths were tolerated, if unfairly taxed.

Greek nationalism kept Alexander’s ancient imperial ambitions alive. In the 19th century, this nationalistic fervor encouraged Greek manifest destiny, which resulted in catastrophe for the fledgling state. First, of course, it had to identify itself as Greek and throw off the Turkish yoke. This act proved almost too much for the competing kleftes and tribal leaders of the Peloponnesus. Without the intervention of European powers, which defeated the Turkish navy at Navarino in 1827, the modern nation of Greece might never have been born.

Mr. Norwich also gives the birth of modern Italy — with its great politician Mazzini and its romantic general Garibaldi — a considerable share of his drama. Europe’s revolutions of 1848, along with the unification of Germany, the revolts against the Ottomans in islands such as Crete, and the rise of Mustapha Kemal, “one of the half dozen most remarkable men of the twentieth century,”are all tied with sanguinary certitude to what was euphemistically known as the Great War, a war fed by virtually every population of our story so far.

Mr. Norwich concentrates on the Gallipoli disaster and the Middle Eastern Campaign with such heroes as T. E. Lawrence and General Allenby, who made a Saladin-like display of compassion when he entered Jerusalem. A footnote reminds us of the 1917 Balfour Declaration, offering British support for a Jewish homeland provided that the rights of other people in the region would not be trammeled.

The rest is history, and we are up to our necks in it, whatever sides we take. Mr. Norwich admits that the Middle Sea has too often been stained with blood, but he also laments the passing of its grandeur and the cultural trivialization of tourism. I can see the point — especially if those beautiful young things at Club Med prove to be ignorant enough of this history to repeat it.

Mr. Mason’s verse novel, “Ludlow,” will be published early in 2007.