In medieval and ancient times, armies would carry dried grains, dried fruits, and salted meats. However, for the most part, they would be fed "off the land." That is, they would either buy food in areas they were passing through, ask vassals for some, or steal or loot from the local population. This limited the size of an army. Disease and malnutrition caused more deaths than combat with the enemy.
Modern-day military rations trace their origins to France, where Napoleon offered a reward of 12,000 francs to anyone who could preserve food for his army. A Frenchman named Nicolas Appert had already worked on food preservation by canning it in 1795. The process involved canning food in jars, sealing them, and then boiling the jar and its contents for as long as necessary to kill any microbes in them and then letting everything cool so that a seal is formed. This process was liked by the French Army, and in 1810, they accepted it for food preservation.
The abbreviation MRE (Meals Ready to Eat) was first used by the US Army in 1981 when they were working to improve on the MCI (Meal Combat Individual) and the LRP (Long Range Patrol) rations that were issued to Special Forces and LRRP (Long Range Reconnaissance Patrol) units in Vietnam. After three to four decades of research and trials, the US Army has about 24 menu options in MREs. Most MREs today also contain certain non-dietary items like a moist towel, waterproof matches, and napkins or toilet paper. A typical MRE contains an entrée like a beef stew or spaghetti, a side dish like rice, corn, fruit, or mashed potatoes, a cracker or bread, peanut butter or cheese spread, dessert, candy, some beverage mix like cocoa, coffee, tea, or electrolyte powder, a flameless ration heater, and a few accessories like a spoon, matches, creamer, sugar, salt, chewing gum, and some toiletries.
The French RCIR (Combat Ration Individual Reheatable, translated to English) is considered to be one of the tastiest military ready-to-eat meals in the world. With 14 menus (7 with pork and 7 without), this ration pack comes with water purifying pills or powder, fuel tablets, waterproof matches, and a disposable stove. Food generally consists of soup, a cereal bar, a chocolate bar, chewing gum, instant cocoa, evaporated milk, freeze-dried coffee, an appetizer, a dessert, a sweetener, and two entrées. Meats used in the entrées are salmon, tuna, mackerel, duck, chicken, beef, and pork, in many variations like salads, pies, and stews.
In the UK, the Operational Ration Pack, or ORP, is used to feed an individual soldier for a day. These are divided on the basis of religious requirements, mission distance requirements, climatic requirements, and meat preference requirements. The ration pack also has a stove that uses hexamine for fuel and is used to heat the breakfast, lunch, and dinner meal items. The three main meals are contained in a boil-in bag encased in a polythene bag. Some of the breakfast, lunch, and dinner dishes are Pindi Chana Aloo, Pork Sausage and Beans, Rajma Masala, Vegetable and Chickpea Biryani, Hunter Chicken, Beef Burrito, Pork Sausage Casserole, Pork Pasta Bolognese, etc. Oatmeal, dried fruit, and chocolate-based snacks are common, along with other staples like instant coffee, teabags, matches, wet wipes, sauce, and water purification tablets.
The Russian Federation issues something called the "24-hour Individual Food Ration" to its soldiers. Known as the IRP-P Russian, it is structured like the French RCIR with plenty of canned food. Ration packs include crackers, canned meats (like liver and sausage stuffing), stewed beef, assorted canned meat and vegetables (like barley porridge, boiled buckwheat, and rice with beef), multivitamins, paper napkins, can openers, hexamine stoves, sugar, tea, candy, jam, and beverage concentrate. This ration type is a direct variant of the "Mountain Ration" issued to Soviet troops in Afghanistan.
In India, the DRFL (Defense Research Food Laboratory) in Mysore has spearheaded MRE development. Pre-cooked thermostabilized entrées with a shelf life of 12 months are packaged in plastic foil laminate retort pouches, as in other countries. Dishes include but are not limited to Sooji Halwa, Chicken Biryani, Kebab, Tandoori Paneer, Dal Makhani, Jeera Rice, Rajma Curry, and Vegetable Pulao. A folding stove and hexamine fuel tablets are also provided. Marine commandos and armored vehicle crewmen are provided with a slightly different type of ration.
Most countries' ration packs have 3000–3500 calories and are generally dehydrated for weight savings and longer shelf life. MREs have a shelf life that ranges from one year to three years. Ironically enough, it is this dehydration that has been a major point of criticism, as soldiers end up consuming very little water throughout the day and are at risk of heat strokes and other heat-related problems. The lack of dietary fiber and micronutrient deficiencies have also been pointed out time and again. Soldiers generally try to eat fresh produce and meat whenever possible; however, operating in austere environments demands some compromises, and that's where MREs come in handy and help nourish a soldier temporarily.