Simply put, field rations are those foods issued to soldiers in the field, particularly in wartime, whether prepackaged or freshly prepared. Being “in the field” indicates being away from static (garrison) facilities.
To define the term “field rations” as only applicable to canned or prepackaged rations is not only overly restrictive, it is historically incorrect. The United States Army for many decades defined field rations as rations not issued in garrison, but still very close in composition to garrison rations. In World War 2 there existed field rations A and B in addition to the well-known prepackaged C, D, and K field rations. Field ration A was defined thus:
“Field ration A.-This ration will correspond as nearly as practicable to the components or substitutes therefore of the garrison ration. This type of field ration will be issued as often as circumstances will permit.”*
Field ration B was similar to Field ration A with preserved or canned foods substituted for perishable foods.
The major distinction between garrison and field rations was not in their component items and cooking techniques, but rather in the types of equipment used to prepare them. The definition was quite similar in most European armies. Prepackaged rations have historically not been intended for continuous use, as indicated by their nomenclature: “iron rations”, “emergency rations”, “reserve rations” etc. Their use was to be limited only to those situations wherein a unit was isolated from the normal food supply. In addition to their lack of variety, prepackaged rations tend to be considerably more expensive than prepared meals. The expectation has been that troops would be fed prepared meals for the majority of their time in the field. Unfortunately, many were the occasions when reality sabotaged expectations.
Prior to the start of the 20th century, technological developments in rolling field kitchens, portable field stoves and food preservation had made it possible to prepare hot meals in very close proximity to the front lines. Further advancements in the mobility and efficiency of military field kitchens caused the distinction between garrison and field cooking to become blurred and often eliminated altogether. It eventually became possible to prepare most, if not all, recipes under field conditions.
*TM 10-405, The Army Cook, April 24, 1942, pg 105, para.68.b (1) (a)