There were always kingdoms and wars in Gaul right up until you submit-
ted to our laws. Although we have often suffered at your hands we have, by
right of conquest, imposed only this one thing on you, with which we
keep the peace. For peace between nations is impossible without soldiers,
and there are no soldiers without pay, and no pay unless taxes are paid.
Everything else we share with you.
(Tacitus, Histories 4.74)
Who paid for empire? Like all imperial rulers, the Romans passed the cost on to their subjects. Romans knew this. Tacitus puts this pithy summary of imperial economics into the mouth of the Roman general Cerealis, in a speech aimed at dissuading the Gallic tribes of the Treveri and Lingones from joining the rebellion of AD 69. This was, indeed, the bottom line. By Tacitus’ day the army devoured most of what the emperors raised in taxation. Put like this, the resourcing of Roman imperialism seems very simple. Yet the mechanisms employed were phenomenally complex and in constant evolution. Roman history is, in some sense, the story of unending struggles to balance the imperial budget. Perhaps this was true for all imperial states.