Roman Legionaries Vs. Medieval Heavy infantry

[M. Demetrius]

Even Napoleon had logistical problems during some campaigns

So have all armies, at all times, including modern. There are a dozen critical supply failures in the "Battle of the Bulge" on both sides that had extreme effect on the outcome. The Romans were better organized than many of their opponents, which had great effect on the campaigns they waged. They sadly underestimated the value of water when fighting the Parthians, and greatly underestimated the horse archers' arrow supply line.