Herrin is a leading Byzantinist, and she presents eastern Rome as a civilisation, with its strengths and defects. Told in a particular way, the story of Byzantium can appear surreal - quarter-century civil wars between blinded grandfather and scheming grandson, manipulated by Genoese and Venetians who use Catalans and Turks as their agents eunuchs leading armies the deranged monks whom Gibbon mocked. She has not tried to follow the path of so many narrative historians, of greater or lesser gifts. The Byzantines regarded theirs as the great civilisation, and Judith Herrin splendidly shows how right they were. When the Turks finally did take Constantinople in 1453, the 'Latins' had in effect weakened the place to the point of indefensibility the gulf between Catholics and Orthodox was so great that, up to the very last moment of the siege, the great Church of the Holy Wisdom, the Aya Sofya as it is now called, had to be kept closed because if the two sides congregated in it, they fought. It was in fact part of the defences put up by the Genoese against the Venetians, who were trying to get into the Black Sea trade, which Genoa monopolised. The Galata tower, built in 1384, is one of the city's landmarks, and you assume that it was meant to deter Turks or even Russians.

The empire lingered on for another 250 years, but in the main it had become a football, kicked around by rival Italians. The Byzantines, convinced of their superiority, could not work out how their semi-savage enemies could be so skilled in such arts.

The Venetians worked out an antidote, treating leather with chemicals that resisted the flames, and enabled ships to approach the great sea walls on the Golden Horn. The Byzantines traditionally defended themselves with a combustible called 'Greek fire', which burned wooden ships and siege-towers. The Fourth Crusade is one of the landmarks in the rise of western technology. The Crusaders sacked the tombs and now there is only a tiny sliver of the original gold left: all the rest was looted and carted off to Italy. In Istanbul they are doing a good job, at last, of restoring the great church of the Pantocrator, where emperors of the Comnenos dynasty were buried. In 1204 the Fourth Crusade, marauding Normans and scheming Venetians, ruthlessly sacked the great city. The Byzantines looked to the west for help, but that again was a sad story. There was a recovery in the 10th century, as the Arabs themselves declined, but towards the end of the 11th century, a good part of Anatolia fell to the nomadic Turks.

Eastern Rome exhausted itself in a long war with Persia, and then lost almost all of its Middle Eastern territories to the Arabs (Muhammad was one of Gibbon's few heroes). It is a complicated story, defeating all but the best chroniclers.

Byzantium by Judith Herrin