According to the general literary sources, the standard military diet consisted of corn, bacon, cheese and vegetables, but the staple was corn, preferably wheat, consumed in the form of bread, soup or porridge (Davies 1971). The military ration has been variously calculated, but a figure of between 59 and 78 lb (c.25 and 35kg) per man/month seems likely (Tomlin 1998). The importance of cereals in the diet of the troops is confirmed archaeologically by environmental evidence from a number of forts (e.g. Elginhaugh and Bearsden; Clapham 2007; Knights et al. 1983); the standard provision in all forts of granaries (though not necessarily restricted to the storage of grain); the presence of numerous baking ovens around the perimeter of forts (though not necessarily only for the baking of bread); and the frequency with which quern stones are attested (although not necessarily only for the grinding of corn). Analysis of the Bearsden sewage suggests the importation of wheat and barley to be ground on site (Knights et al. 1983). It remains to be established how much locally-grown grain was used.
Meat may not have formed as significant a part of the military diet as has often been assumed, with perhaps a daily ration of only 0.13 lb (c.0.06Kg, 60gms; Groenman- van Waateringe 1997) and this is supported by the evidence from Bearsden (Knights et al. 1983). Bone evidence from Britain generally indicates a preference for beef and pork amongst the military, with pig and sheep/goat making up the bulk of the remaining 10% (King 1984, 1999; Stallibrass 2000). What bone evidence there is from Scotland, limited by its generally poor preservation in acid soils, provides broad confirmation. Occasionally, where conditions of preservation are favourable, other species are attested, including birds, game, fish and shellfish (e.g. Ewart 1911).
Evidence of the consumption of more exotic, imported items is variously attested. Olive oil and wine were essential elements of the Roman diet and are well attested by the recovery of amphorae. Some imported luxuries are also indicated from environmental evidence, including figs (at Bearsden and Elginhaugh). To balance this, several types of locally available wild fruits were consumed (Dickson and Dickson 1988).
Cool (2006) has shown the value of taking an integrated approach to the evidence of eating and drinking. There are the ingredients for a more complex and subtle picture of military diets in the existing archives, both from fresh study and from the application of scientific techniques such as residue analysis (eg Cramp et al. 2011) systematically to old and new finds. In the event of skeletons being excavated, these too can now cast important evidence on questions of diet.
Food preparation is attested by the frequent recognition of ovens around the perimeter of forts set against the back of the rampart, usually in groups of two or more (e.g. Doune, Elginhaugh, Fendoch, Inchtuthil). Recent work at Elginhaugh suggests that each cavalry barrack probably shared two ovens (Hanson 2007, 193). At Bearsden, the lack of ovens may relate to a different style of cooking; in this case there is evidence for braziers, suggesting African-style casserole cooking (Swan 1999). The widespread distribution on sites of pottery and quernstones indicates that both the preparation and consumption of foodstuffs was a dispersed activity, possibly by century or contubernium. Vivien Swan has suggested that one can identify a consistent pattern within military coarseware assemblages representing the standard ‘issue’ of a specific range of coarseware for a group of soldiers in a contubernium, including jars and lids for storage and cooking, mortaria and other forms of bowl for mixing, shallow dishes, flagons, beakers and, cups for food consumption (2008, 49-51).
Many excavations took place before the days of improved retrieval of environmental evidence, so there is a good chance that new excavations (at likely locations on the old sites) will produce significant material. The need for well-designed environmental sampling programmes on modern excavations should be self-evident, but bears repetition.