The Jungle Ration (or "J-Ration") was a dry, lightweight United States military ration developed by the U.S. Army during 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 showed 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 to purify the 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 , and weighing about 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 waterproof 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. 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