Soldiers would usually receive up to a weeks rations in one issue. Grain was ground in a rotary mill - each eight man squad (contubernium) had one mill, which was carried around on a mule, together with the squads tent, cooking cauldron and any other equipment the soldiers could secretly offload from their own packs.
Bucellatum
Grain was usually baked into bucellatum (hard tack). This frugal food was quite often the mainstay of the Roman army. Consisting of flour, a little salt, just enough water to convert it into dough, and a dash of oil, it was shaped into circles and baked until rock hard in texture. Bucellatum could keep for months and even years if stored correctly.
It was so hard and flavourless that modern re-enactors sometimes jokingly say that Rome's legionaries conquered the world in search of condiment. Bucellatum was probably only eaten 'straight' when cooking was out of the question. More commonly, it was boiled with meat or vegetables - in essence, used as a thickener for stews - or softened by soaking it in a little water, vinegar or oil before being eaten.
Wheat was the favoured grain of the Roman army. Barley was only issued if there was no wheat available, or as a punishment. Legionaries must have had at least some love for their tough fare: at one point during Caesar's Gallic campaigns, grain was scarce and the men were fed largely on meat. Surprisingly, many veterans grumbled at this, demanding to know where their grain was.
Other legionary foods
Soldiers were also issued with oil, usually olive oil. Oil would have been important, providing men on a lean diet with much-needed fat. The salt ration - (salarium) has possibly given us the modern term, salary.
Other foodstuffs included beef, pork, venison, and fish. Meat could be fresh or preserved by salting and drying. Fruit and vegetables were usually eaten seasonally, although fruit was also dried to preserve it. Most of these items would have been furnished by the soldier himself, either foraged, bought or stolen.
Legionaries also received a 'sour wine' ration. This was wine that had virtually turned into vinegar. The Roman taste for strong, harsh wine was often commented on by other ancient cultures. The wine ration was usually mixed with water in the soldiers canteen. The gesture of the legionary who offered Christ a vinegar-soaked sponge on the point of a spear whilst he suffered on the cross has often been interpreted as an act of cruelty. The soldier may well have been trying to provide him some relief - one of the consequences of crucifixion was raging thirst - by offering him a drink from his own canteen.
It has been estimated that the average ancient soldier probably recieved roughly 3,500 calories of sustenance a day.
The Roman Army
http://www.roman-empire.net/army//army.html
Soldiers Lives through History - The Ancient World
Richard A.Gabriel
Greenwood Press, 2006
