About midnight
All day , therefore , he remained quiet in his camp ; but when evening approached , he ordered his troops to take some refreshment , and , smiling , told them ` to dine like men who were to sup in another world . ' They then completely armed themselves , and waited for the middle of the night , which Leonidas judged most proper for the design he meditated . He saw that the Persians would never imagine it possible that such an insignificant body of men should think of attacking their numerous forces ; he was therefore determined , in the silence of the night , to break into their camp , and endeavour , amid the terror and confusion which would ensue , to surprise Xerxes himself . `` About midnight , therefore , this determined body of Grecians marched out with Leonidas at their head . They soon broke into the Persian camp , and put all to flight that dared to oppose them . It is impossible to describe the terror and confusion which ensued among so many thousands thus unexpectedly surprised . Still the Grecians marched on in close impenetrable order , overturning the tents , destroying all that dared to resist , and driving that vast and mighty army like frightened sheep before them .