Supply in Hellenistic armies

The main question I've been asked pertaining to this blog concerns the logistical problems underlying the numbers of troops at battles like Raphia. Regardless of source credibility or textual criticism, the sheer numbers involved in major battles beg questions concerning supply. This problem will come up again in my TWAW entry this week, which will concern the Battle of Cannae.

There are several logistical sorts of questions we can ask about ancient armies. I'll answer each of these in relation to the Raphia campaign.

1) Population - could the states involved have actually committed the numbers of soldiers described in the account?

Both the Ptolemaic and Seleukid armies were stretched to raise their forces for Raphia, but the numbers were not beyond the ability of what were, at that point in time, the largest states west of India. Population estimates put the population of Ptolemaic Egypt at between 5 and 7 million at this time, which means that we might expect a military-eligible population in the range of 1 to 2 million. But this number is actually more complicated. The vast majority of those men would have been Egyptians, of whom the machimoi (warrior class) only numbered several hundred thousand. So only a small number of the machimoi class were mobilized for the Raphia campaign, roughly 1 in 20. The mobilization would have heavily stressed the non-Egyptian population of Egypt. For example, P.Count establishes that the number of cavalrymen settled in the Fayum, one of the most important sites of military settlement, was in the neighborhood of 3,500 during the latter 3rd century. These settlers would have provided many of the non-mercenary cavalry raised for Raphia, and if the P.Count and Polybian numbers are both right, most of them served at Raphia. The other settlers, accounting for just over 30,000 soldiers, would have similarly stressed the Ptolemaic Hellenistic or Hellenizing population. It over-extended the military settler system, forcing the Ptolemies to recruit from their non-military population (the "epigonoi," or descendants) in order to reach their full complement. It is possible that there were as few as 100,000 military age, able-bodied men in the non-Egyptian population. If that is the case, as many as 1 in 3 went to Raphia, which would put a considerable stress on the expedition. For this and other reasons each side sought out the decisive battle, and even the victorious Ptolemies did not seek to carry their advantage very far after the battle.

2) Food Quantity - how much food would each soldier, horse, attendant, and elephant eat?

While a modern American soldier might consume 3,000 or more calories in a day, the ancient soldier likely ate considerably less, and attrition was much higher (estimated to be as high as 15% in Roman Republican armies over the course of a major overseas campaign). Engel's study of Macedonian logistics concluded that a well-supplied army would provide 1.5 pounds of bread for every soldier every day. With 70,000 soldiers, we're dealing with 105,000 lbs. of bread per day, or 52.5 tons. That's 367.5 tons per week. Only a powerful economy could sustain that sort of supply for more than a few days. And Egypt was indeed the breadbasket of the Mediterranean, producing tens of thousands of tons of grain every year.

3) Food Transport - how did the armies get the required foodstuffs to their destination, and how did they continually resupply these troops?

Individual soldiers, and occasional attendants, could carry some of their food themselves. But within a few days the army would be dependent on supply trains. For the Ptolemies, even this was not a major problem. They left their military camp at Pelusion, with its large store-houses, which had been in existence since Pharoanic times, to head east. They traveled about 115 miles before coming into contact with the Seleukid army. For most of that trip, which may have been made in a week, the Ptolemaic army would have been in direct contact with naval resupply ships. The Ptolemaic navy controlled the sea, especially that close to Egypt, and could protect large supply ships bringing additional grain, if such a need arose.

The Seleukid army faced greater problems. They too used the coastal roads in that campaign, and could be resupplied by ship or supply train. But their supply situation was not simple. They encamped first at Gaza, where Nabataian Arab trade routes terminated, and where they therefore could have gotten access to needed foodstuffs. But this source of supply would not have been as reliable as a royal resupply via ship or land. Ship resupply would have been difficult once the armies drew up near one another, since the Ptolemaic navy could threaten the Seleukid ships. And large supply convoys would have faced a harrowing journey through the coastland of Palestine. For that reason, we can look at one aspect of the battle and revise the traditional narrative.

Revising the Initiation of Battle

The Seleukids pushed for the start of battle. They moved their camp forward from Gaza to Raphia, bringing the two camps within sight of one another. They drew out their army first to being the attack. And when the two armies were drawn out, the Seleukids started the battle. Polybius' narrative, and the narrative that has traditionally been most popular, is that Antiochos III desired to start the battle because he was a good general, a zealous warrior, and questioned the quality of the Ptolemaic army. But what we see from looking at logistical concerns is that the Ptolemaic army could have maintained a standoff considerably longer than the Seleukids could. If the Seleukids were to seek decision to the war over Syria, they needed to seek out battle before their supplies ran low. This logistics-driven narrative is an attractive alternative to the personality-driven narrative which has generally held greatest sway.