For the past two centuries Herodotos’ account of Xerxes campaign in Greece has received little better than caustic skepticism from scholars. On close inspection this view can be shown to be entirely unjustified, being based on nothing more than pure guesswork. Only two efforts have been made to analyse the Histories scientifically, but both these are based on assumptions that are partially invalid. This is the first work that seeks to discover the validity of Herodotos’ estimates, using verifiable assumptions and simple computations.