Grain can be turned into porridge (so basically just soaked) and eaten, bread and beer is optional. In fact, IIRC classical-era armies would eat their grain as

Grain can be turned into porridge (so basically just soaked) and eaten, bread and beer is optional. In fact, IIRC classical-era armies would eat their grain as porridge instead of spending hours in camp baking it into bread. For obvious reasons.