The logistics of Xerxes' army remain shrouded in the silence of the sources. On their side, Persians left little testimony of their own history. The Great Kings relinquished control of their historical memory to others; and on the Greek side, there are limits to the logistical information Herodotus gives. The lack of Persian sources is not surprising. This is a story after all that no Persian would clamor about; reminding the royal house of its defeats and misadventures could easily lead to a sticky end.

The logistics presented here are a piece of historical fiction, of necessity, because attempts to give a number for the size of Xerxes' army scatter all over the map and are almost hilariously unconvincing. Shaky guestimates can be less useful than fiction. That is right, a fictional logistical plan that sees the army fed and provided in a feasible way, as I intend to present, provides at least an antidote to the habitual quick dismissals of Herodotus' numbers and their characterization as a fantasy or a joke. If instead, numbers are feasibly within the capabilities of Persia's war machine, the question about the size of Xerxes army becomes rather, how near it really was to Herodotus' number, rather than how far.

Within the blur of uncertainty that attains history, some questions may become clearer when reduced to a binary choice like: feasible or not feasible.

There is no escaping having to leave to interpretation historical arguments no matter how objective numbers may appear. In the end, it is about whether ideas conform to reason and doubt is reasonable, something we usually leave to a jury of others. In our favor, Herodotus shows he possesses an inquisitive and rational mind of sound intellectual qualities.

In the 6th century BC, he Ionian city of Miletus was home to a group of freethinkers, among the first to decide that trusting the intellect was the best guide to action and a good way to live. Miletus became the center of the Ionian school of Pre-Socratic philosophy, and it was only 35 miles north of Halicarnassus, the Carian and Dorian Greek town (modern Bodrum, Turkey) where Herodotus was born. It is fair, therefore, to count Herodotus as part of the Ionian intellectual elite; a fact underlying, I believe, the method of his inquiries, as scientific and rational as they could be.

WHAT NUMBERS?

Herodotus gives sizes for both the Persian army and navy and also for the attendants and camp followers. In all can easily amount to five million souls. But Herodotus himself points out the his numbers for army attendants and camp followers are suppositions, unlike combatants which Xerxes actually counted during his stop at Doriscus in Thrace. We are concerned only with the numbers that are not suppositions and given as firm round numbers, the infantry count is in fact the result of a census, which Herodotus describes in details (Hdt. 7.32), taken by filling an area for 10,000 soldiers 170 times. So, what are the numbers under test?

The Quartermaster's job therefore, is to keep 1,800,000 combatant souls fed and in operational condition, and marching to their military destinations without unplanned interruptions.

The number of servants, attendants and the commisariat personnel, and the number of pack animals we will derive from the requirements to provide for the combatants, as we go along.

THE MARCH

Time and space considerations define the character of the march as much as the configuration the Quartermaster chose, and the sort of occasion the King wished it to be.

Xerxes March from Sardis to Thermopylae was approximately 800 miles long. For terrain analysis we divided it in three segments, (1) Sardis-Abidos, (2) Abidos-Doriscus, including the crossing of the Hellespont, and (3) Doriscus-Themopylae.

The march took place in spring and summer. Setting out from Sardis in late March, crossing the Hellespont a month later for a final arrival at Thermopylae in September, after lengthy stops at Doriscus and Therma.

Xerxes' March seems to consist of (a) a large military parade along the king's dominions and friendly territories and (b) a smaller, inner battlefield force to invade Greece, to go into hostile territory beyond Therma. This makes sense as alleviates the need to support large numbers by sea, where the fleet would be less able to do so, if at all, due to the difficult sea coast in Thessaly.

If from Sardis to Doriscus, the march was a parade to impress the king's subjects, combatants may have marched in full regalia, without carrying any other equipment or provisions, leaving it to the baggage train to transport.

The march benefitted from long years of preparations, three intense years under Darius and four years under Xerxes, including unexpected field practice to quell a short-lived rebellion in Egypt in 481 BC. In these preparations, imperial officials conscripted men from all the king's lands and allied nations, dug the Athos canal, built the four Hellespont bridges, and prepared food depots along the path of the march, and a large fleet of transport and war ships made ready to supply the army and attack Greece by sea. The sources give no detals of the less visible teams of messengers, scouts, surveyors, planners and future guides, who chose the itinerary and camp sites along the way, for each prong of a march and well ahead of time.

When the Persians absorbed the New-Assyrian and Neo-Babylonian polities into their empire, the conquerors learned a great deal from them about the movement and supply of large armies over great distances, and put their acquired skills into practice. [...] and so improved on the old Assyrian routes, for example the two thousand kilometre “Royal Road” from Susa to Sardis, that they were able to move large numbers of troops and supply them across the wide expanses of their empire. Manning (2018).

Stage 1: From Sardis To Abydos

Stage 2: From Abydos To Doriscus

The second stage of the march starts with the crossing of the Hellespont. As contingents arrive in Europe by the egress points of the pontoon bridges, they begin the march north-west along the Gallipoly Peninsula. Herodotus' description of the Crossing of the Hellespont remains consistent with the given size of the army. On the European side, the column of combatants and the accompanying baggage train resume the march over land heading for the army base in Doriscus, Thrace. The Gallipoly Peninsula's ancient name is The Chersonese, and is perhaps the driest segment of the march, relative to the abundance of rivers and lakes found in other stages of the march.

Stage 3: From Doriscus To Thermopylae