Why were medieval armies so much smaller than classical ones? Like cannae and asculum saw 40-80000 men per side. stevenattewell Uncategorized September 21, 2016 1 Minute Discussed here and here. Short version: because feudalism. Share this: Share on X (Opens in new window) X Share on Facebook (Opens in new window) Facebook Like Loading... Related Published by stevenattewell View all posts by stevenattewell Published September 21, 2016