Difficulty in retrieving supplies for large armies often comes up as an issue when hearing about Roman warfare, and I often hear about those armies supplementing what supplies they had with foraged and pillaged food and supplies.
How did armies coordinate hunting/gathering/foraging? How were supplies from foraging distributed? And the biggest thing I'm having trouble understanding is, how did armies of thousands possibly sustain themselves for long(ish) periods by foraging? Even if on the move it seems like there couldn't possibly be enough food without going miles and miles out. And if during a siege, I would think that crops and foodstuff in the immediate vicinity would be decimated in a very short amount of time, did they simply keep casting a wider and wider net, going further for food each time?
Edit: another question I thought of. How did camp followers and the like get a hold of possibly foraged supplies, considering they did not have direct affiliation with the military?
In both the Principate and Late Antiquity, Roman armies did not sustain themselves through foraging.
Your thought process here is totally correct, as it would have been impossible for Roman armies of any size to sustain themselves through foraging alone. Julian’s army at the Battle of Strasbourg in 357 A.D. was only about 13,000 strong (10,000 infantry and 3,000 cavalry), yet is estimated to have consumed, daily, thirty tons of grain, thirteen tons of fodder, and 30,000 gallons of water. This is a minimum- consumption levels could have been higher, and this estimation includes only fighting men and horses. It would have been nigh impossible for armies to forage daily for such a quantity of supplies. When operating inside Roman territory, foraging was discouraged, as the army naturally did not look favorably on stealing from taxpayers. While foraging most certainly did happen when operating in foreign territory, it was viewed as a supplement to official rations, rather than the principal means of their acquisition.
Roman armies thus relied upon pre-prepared supplies. In Late Antiquity, the collection of military supplies (grain principally, but also clothing, weapons, and other equipment) was the responsibility of the regional Praetorian Prefect. In peacetime, the civilian officials under his command oversaw the collection and distribution of supplies to military units, although units themselves could also directly requisition them. The use of stored supplies allowed Roman forces to operate year-round, although offensive operations were principally conducted in the summer months. In preparation for a campaign, a Prefect’s civilian staff would oversee an additional stockpiling of supplies. When organizing his campaign against Julian in 360, Constantius II ordered the stockpiling of three million bushels of wheat to feed his army. Such a high volume required much organization, and it is a testament to the sophisticated nature of military logistics (and it’s efficacy) that no Roman force in Late Antiquity is recorded of suffering from extreme supply shortages. Often, supply depots were established along an army’s route through friendly territory, to reduce the size of the baggage train.
Individual soldiers carried on their person around twenty days rations, along with any other personal equipment. This was intended to further reduce the size of the baggage train, and to allow smaller forces to operate independently (temporarily) of supply lines.
The remainder of an army’s supplies (foodstuffs, fodder, water, clothing, weapons and other equipment, along with officers’ baggage) would have been carried by the wagons of the baggage train. While the existence of the baggage train would have greatly reduced mobility, it would also have allowed a Roman army to operate for a far greater period of time than most of it’s opponents. Indeed, the highly sophisticated nature of it’s logistical system gave Rome a distinct advantage over the bulk of it’s enemies.