Persian Invasion of 480 BC - articles

[Felix]

It is a scientific fact that a healthy man needs at least 3 lbs of wheat or the equivalent a day when doing heavy labour. If he gets less than this, than he slowly starves. Historical precedents support this.

This makes sense, but the man is going to need most of this no matter how he might be employed. That's the thing. An empire has X amount of men and pack animals doing whatever it is they do, and I don't see how moving them to a concentrated location into foreign territory drastically increases their needs. I'm sure that food of various types was transported all over the vast Persian empire, making a trip to Greece cannot be a big deal transport wise. If you were marching across a wasteland, there would certainly be a limit to how far you could penetrate, but you're likely to find some nice grazing land and water on the way, which would extend your range by quite a lot. As your food load lightens, you can also get something back from eating the extra pack animals. That might seem kinda gross to eat a mule, but Xerxes men were eating grass and tree bark on the way back. Not fun.

If a few dozen miles was the extent that grain could be transported without eating it all, there could be no profitable land-based trade in grain, or any type of food, which I'm pretty sure there was... Am I wrong?

Bulk food was not transported by land any great distance. Take the extreme case - traveling in the Arctic or Antarctic. There is a fixed distance beyond which it is not possible to travel, if one has to carry all of one's supplies at the start. (This varies with terrain, but is relatively constant in terms of number of days.) The way this was overcome was by creating caches of supplies along the route. In pre-industrial times, water transport was essential to the bulk transport of goods; the effort of actually bearing the weight was done by the water, and wind and current could supply power without burning up food or fodder. Long distance trade in pre-industrial times was mostly in luxury goods, or by water.

Now, in your own empire, moving a large army is possible since you can create caches of food along the route from the local sources (assuming these lands are not famine stricken). Even so, large forces have great difficulties. As Engels shows in his book, Alexander was careful to move into lands which had available food, and sometimes sent emissaries ahead to bargain with the locals and make sure food was gathered for his forces before they arrived - with the tacit threat of violence if there was no cooperation. Xenophon mentions the same technique, on a smaller scale.