The 300 story isnt really THAT fictional. There were 300 spartans and maybe a 1000 others, if that, that stood against a massive force of Persians and held them. There are contempary sources that quote the persian number at 1 million although this is widely dismissed as being logistically unfeasible although the force could quite easily have been over 100,000 men. No one actually knows the figures for definate but its not unthinkable that the Persian Empire could have picked up well in access of 20,000 men on his march to Greece. Dont forget most of the troops were commoners and didnt really have any choice as to whether they followed. Yes the film was nicely flowered but the gist of the story remains.