It’s mind-boggling to try to contemplate the massive forces Xerxes took with him from Persia into Europe. Whether the numbers Herodotus provides are accurate or not, the facts still remain—these masses of people drank rivers dry, left famine in their wake, and went on for miles when lined up. According to Herodotus, it took them a week to get the entire army past any given point.
So for those years when they were gathering the army and then marching into Greece, the forces lived the life of nomads. They put up and took down tents for each night—though purportedly, Xerxes’ was still so resplendent that the people he visited were awe-struck by it. They took food and water from wherever they were, yes, but also amassed supplies for years before the march began. Stock piles of grain and other foodstuffs were stored at key places along the journey, and supply vessels sailed alongside the army.
Even so, the food ran out—due in part to these vessels being destroyed in the storms of the Hellespont—and by the time Xerxes marched home, his forces were decimated by disease and hunger.
Each place Xerxes stopped, a feast was expected to be provided by the locals. They spent months getting everything ready, presented it all to the king in one meal, and then the next day Xerxes would take with him everything they had provided and move on to the next lucky hosts. In his wake he left empty fields and a people depleted of what luxuries they had once claimed. Herodotus quotes someone as saying something like, “It is a good thing he only requires one meal a day, or we would never survive it.”
(Map of the empire at time of invasion)