The battle of Thermopylae was not a  normal battle consisting of two armies charging at each other and having a blood bath until one of the sides is completely wiped out. Although this battle still had most of the same characteristics as those battles, it did not end in a blood bath. This battle did not even start the way the Persians thought it would nor did it end the way the allied Greek nations thought it would. It started that day with Darius' the Greats son Xerxes sending a scout to observe the Greeks. The forces on the Greeks side included: the Spartans, the Mantineans, the Tegeans, the Arcadian Orchomenos, the Corinthians, the Floians, the Mycenaeans, the Thesbans, the Thespians, the Phocians, and the Opuntan Locrians. All together there were 6,400 soldiers on the allied Greek forces side. On the Persian armies side there were 2,641, 610 soldiers. You have read what impact the battle of Marathon had before this war, and the real conflict is that the Persian army, commanded by Xerxes, were shocked and mad at themselves for having lost to the Greeks. So in turn, they took an army and chased the Greek army. The Greeks led them to the pass of Thermopylae and from there they did battle. The results were this: the Persians did win, but as a sacrifice suffered many deaths to their army which strongly decreased their numbers,  which were their strength as an army. On the other side, the Greeks lost the battle, but did not suffer as many deaths as the Persians did, which kept them fresh for the rest of the war. They later would be thankful for this.