Estimating Rome's enormous army and support train

The combined consular and proconsular forces probably included ten to twelve legions, corresponding allied formations, and tens of thousands of supporters. Several estimates based on different legion and allied-unit strengths are more useful here than one uncertain headline figure. Depending on those assumptions and the size of the support train, the total population in the two Roman camps may have approached two hundred thousand. Ancient casualty reports provide firmer evidence than the missing strength returns, but they still require caution. The calculation makes clear that Arausio was a logistical disaster involving soldiers, allies, servants, and other camp followers on an exceptional scale.