Jungle ration The Jungle Ration ( or " J - Ration " ) was a dry , lightweight United States military ration developed by the U . S . Army in World War II for soldiers on extended missions in tropical regions . Origins , development , and use . Prior to World War II , during field exercises in Panama and other jungle regions , it was determined that standard heavy canned or ' wet ' rations were unsuited to soldiers on foot carrying out extended missions in jungle or tropical environments with an abundance of water sources . Testing in Panama by units of the U . S . Army soon discovered that a dry ration that could be easily decanted into waterproof bags for individual use would best suit jungle infantrymen carrying their own supplies while on foot , to be rehydrated as necessary from local water sources . The Jungle ration was originally based on foods carried by American civilians , such as geologists and engineers , prior to World War II . Lightweight , ready - to - eat dry foods appealing to American palates and selected for their bulk when rehydrated were included in the menu , such as dried beef , peaches , apricots , and dehydrated whole milk . Water purification tablets were carried in order to purify water required for rehydration and drinking purposes . After extensive field testing in the Panamanian jungles , the Jungle ration was finalized at the U . S . Army Quartermaster Branch ' s Subsistence Research Laboratory ( SRL ) in Chicago , Illinois , resulting in a daily energy total of about 17 , 000 kilojoules ( 4000 kilocalories ) , and weighing about 1 kg ( 2 lbs ) when packaged for shipping . The Jungle ration was designed to be compact and to feed four men in one day . A can opener , matches , toilet paper , and cigarettes were packed in each 10 - ration waterpoof box . In the original issue of the Jungle ration , all food components were dried or dehydrated and could be decanted from their tins or packages into individually carried lightweight waterproof bags ; this practice greatly decreased the total weight , yet the foods would still keep for several weeks in jungle heat and humidity . In general , it was favorably accepted by soldiers during experiments with the testing platoons in Panama . Among Australian forces , who were briefly issued the ration in New Guinea , the Jungle ration became known as " the Christmas package " for its varied components , which were appreciated after a steady diet of hardtack and tins of corned beef . However , because of its expense and specialized nature , the Jungle ration , like the Mountain ration , was never popular with the U . S . Army ' s Quartermaster Command , who were forced to expend additional funds for procurement and storage of what they viewed as an overly expensive , redundant , and limited - issue field ration . The Subsistence Research Laboratory staff in particular criticized the Jungle ration for not being packaged from the processor for immediate distribution to an individual soldier fighting in a foxhole or other defensive position , as for example , the K ration . This criticism arose as a result of the Army and Quartermaster Corps ' own failure to incorporate previous infantry field reports and test data to SRL staff and dieticians . As none of the SRL personnel had ever served as infantry foot soldiers carrying their own loads through jungle terrain , they were unaware that the primary rationale of the Jungle ration was to provide a palatable , lightweight dry ration that could be broken down and carried in waterproof bags for extended patrols in heavy jungle . During its short existence , the Jungle ration was repeatedly altered with heavier , less expensive canned components by the SRL at the direction of Quartermaster Corps staff , defeating the purpose of a lightweight dehydrated ration . Replacement of the dried beef component with processed , tinned pork or beef in 1942 , followed by elimination of the dried fruit component , caused a predictable nosedive in the popularity of the Jungle ration . It was finally discontinued completely in 1943 in favor of the K ration . The absence of a lightweight , yet sufficiently nourishing and palatable compact field ration would have serious consequences for some U . S . troops later in the war , most notably the soldiers of Merrill ' s Marauders . Menu contents . The jungle ration was repeatedly altered during its existence , as Quartermaster Corps officers substituted less expensive or heavier canned components ( such as evaporated milk ) . Some known components include :