Field Feeding System
During and after the World War II era, the Army created mess sergeants without experience in balancing menus and managing accounts.

Under the circumstances the Army decided it would be more effective to use standardized menus, with each unit receiving the same meals per day. The mess sergeant reported the number of meals they expected to serve and the subsistence supply point issued sufficient food supplies to them to support feeding those personnel that menu.

This became the Field Feeding System. With very few exceptions it was adopted throughout the Army, and it remained in use until the 1970s. Then the Army re-discovered the virtues of allowing a trained dining facility manager to design his/ her own menus within the monetary allowances. This became the Army Ration Credit System.
Combat Feeding
When they were overseas , the company mess teams went with their units, even in the infantry. Wherever possible they cooked meals in the company rear area and distributed them to the front lines. The new equipment, such as the M2 burner and mess tent, made the work more efficient and effective.

Supplying the rations’ ingredients was always a challenge. When possible the Army preferred to use fresh foods, but this required refrigeration facilities, ice plants, or local purchase of vegetables. Canned foods were less desirable, but used when the situation required it.
Often the tactical situation prevented the production of freshly prepared meals. In that case, Soldiers consumed the operational rations discussed earlier. Not surprisingly they grew tired of the monotony, and greatly appreciated the fresh meal as conditions permitted it.
Holiday Meals
Even in combat

A tank delivers the turkeys.
Improved Operational Rations (WWII)
New options for WWII included the C ration and the K ration which were packaged for an individual Soldier, and rations for small groups.

The C ration had canned meats and canned bread units, with candies and accessories. The meals lacked variety and included corned beef, hash, or spam in the meat products. Although the food improved over time, the ration was not well liked.
The K ration was a lighter weight package of off-the-shelf, nonperishable foods such as cured sausages, breads and candies.

It was packed in breakfast, dinner, and supper boxes. It was intended for situations where light weight was required.
The 5 in 1 and the 10 in 1 rations were canned products for groups of five or ten Soldiers. However the low calorie content meant the 1
0 in 1 ration was often fed to groups of just eight Soldiers.
D Ration
Not every idea is a good idea. The Army learned this with the D Ration.

The Subsistence Laboratory wanted something the Soldiers could carry for emergency use. It need to be lightweight, and they wanted the Soldiers to hold it for a true emergency. The concept called for a concentrated chocolate (with little sugar) combined with powdered milk and oat flour. It intentionally tasted bad so that Soldiers would only use it when left without any other choice. In practice, Soldiers just threw it away.