I certainly don't disagree with the fact that the numbers may be a little high, yet ancient scripts state that the army was so large that the ground shook as the army marched, It also mentions thousands of ships. These could easily being over estimations however there is no doubt that the army differences were substantial enough to be a considered a heroic victory for the Greeks as well as a disastrous loss for the Perisans. The movie 300 throws the true history of what happened away but the truth is the Spartans were literally born for war, trained from birth, as well as the fact that the Greek armies of the time employed the most successful type of formation, the Phalanx. Basically a solid wall of spears and shields, the shields themselves had holes cut into the side to allow spears to sit through without exposing the man to the enemy weapons, as one man falls and he is simply replaced. The men in the front simply stabs forward at the enemy in front while the man behind him attacks over the top and downward. One of the only ways to beat this defensive wall is to flank it, but since Thermopylae doesn't allow for any manoeuvrings around the Spartans and supporting Greek troops. The Romans themselves basically copied this type of defense as it was proven that it could hold back enemy. The basic job of such troops or formations were simply to hold the enemy in place and wear them out and hope that the calvary quickly flanks the enemy supported by lighter troops able to move much faster then a standard heavy soldier, spartans were considered to be light soldiers due to the fact that they were no chest armour, only the simple hoplite shied, helmet, greeves, and sometimes bracers, much the same as any Greek hoplite of the time. On the persian side they employed many different types of units many pressed into service, many of them simply slaves, making them easy prey for the warlike Greeks. They used basic armour and weapons, with little training, fighting trained and well equipped and led men who lived for war. A good comparision for ww2 is imagine a 10 militia units taking on 1 crack unit of the same makeup, then imagine it as a bottleneck, who is going to win? THe Greek were the crack units, while the persians were the militia, of course they naturally had there own crack units. Crack units are evident throughout history with few holding back many in many different times in many different wars, what makes this any different. The point throuhgout this whole post is simply an explanation as to how the greeks would have held the Persians and caused them so much hassel. As for the logistics, most of the time Ancient armies lived of the land, raiding farms, cities and what ever they could get there hands on, but it still would be a nightmare to supply a 10,000 man army let alone teh supposed 1 million, which I doubt that was the amount, I have read other notes which put it around 50.000 which is far more believeable, but this contricts historic scripts.