Alexandria is said to have been besieged during fourteen months, and to have cost the lives of 23,000 Arabs. It was never cut off by sea from assistance. The Arabs had neither besieging engines nor a fleet. But Heraclius, who was dying of dropsy, instead of sending a fleet to save the last hold which he had upon Egypt, sent a bishop to make terms with Amrou for his retirement. “Bishop,” said the Saracen leader, “do you see that obelisk? When you have swallowed it I will retire from Alexandria.” The city fell in 640, and since Omar had the library of the Persian monarchs at Ctesiphon thrown into the Tigris, there is no reason to doubt the fact recorded that he fed the 4000 baths of Alexandria during six months with the treasures of Greek literature. An uninterrupted peace since the destruction of the Serapeium, 240 years before, had allowed that city in the world which was most devoted to literature and the richest in commerce ample time to collect the greatest of libraries. The double destruction suits exactly the character given to Chalif Omar by Arab historians. Amrou was not allowed, by Omar’s prudence, to live as governor of Egypt at Alexandria. Fostat—that is, the Tent—where he had dwelt during his siege of Babylon, developed from being the seat of his government to the present Cairo. But to the west Amrou extended the Saracen dominion over Barca and Tripolis. Omar reigned ten years, a Chalif at whose words of rebuke his strongest commanders quailed, and he ruled a kingdom which he stretched in these ten years from Tripolis to the Indus; from the Caspian Sea to the Cataracts of the Nile. He destroyed the Sassanide empire; and the sword of Mohammed, wielded by his second chalif, cut in two the empire of Heraclius. With the loss of Syria, Mesopotamia, and Egypt, the successor of Constantine was reduced to shelter himself behind the walls of Byzantium from the Saracen host, which perpetually plundered his provinces from the Bosphorus to Mount Taurus. During the Roman dominion of many hundred years that vast territory had been in climate, as Herodotus a thousand years before had said of it, the garden of the earth. It had, further, been studded with cities rich in monuments of Greek civilisation. Afterwards these came to be ruled by bishops, many of whom descended from the preaching of St. Peter and St. Paul. Now all this territory lived in anguish at the thought of Moslem incursion. Only the invention of the Greek fire, kept a secret, saved Byzantium itself from suffering in the latter half of the seventh century the doom which fell upon it in the fifteenth.