If we are to seek “turning points” in the history of the empire over which he ruled, there are plenty of options. One landmark was the edict of Caracalla of a.d. 212, when citizenship was radically redistributed in the provinces. Another was the Crisis of the Third Century, when Rome juddered, split, almost collapsed, and then reformed. A third was Constantine’s reign, when Rome adopted Christianity and the new capital, Constantinople, ensured that the hub and the future of the empire would subsequently be found in the eastern Mediterranean rather than the west. And a fourth (as we shall see
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