The D ration is one of the well known rations of WW2. Developed as an emergency ration, it was intended to replace a missed meal. Development begun in the mid 1930's and in 1937 a fortified chocolate bar was standardized as "U.S. Army Field Ration D". Since it was developed by Captain Paul P. Logan (in collaboration with the Hersey Chocolate Corporation) it was referred to as the Logan Bar before official adoption. It is more commonly referred to as the D-bar.
Basically this was a 4 ounce chocolate bar with raw oat flour added. The addition of oat flour raised the melting point of the chocolate from 92ºF (33ºC) to 120ºF (49ºC) so it would be usable in the tropics. Because the flour absorbed most of the cocoa fat it made the bar more solid and stabilized the keeping qualities. But it also made the bar hard to bite through. The reason to use oat flour over other cereals is because oat flour is over 90% assimilated in digestion, therefor more nutritious.
Two thoughts on palatability occurred. One idea is that the ration should not be tasty. The fear was that soldiers would not save the ration for an emergency situation, but rather consume the ration too early as a candy snack. The other thought was that a ration not eaten because it was too unpalatable was worse than no ration at all! finally it was decided that a little flavoring could do no harm.
The formula for this concoction remained unchanged through out the war. Here's what in it (parts by weight):
-160 parts Plain Chocolate ( 54% cocoa fat)
-160 parts Sucrose
- 30 parts Added Cocoa Butter
- 20 parts Raw Oat Flour
- 70 parts Dried Skimmed Milk Powder
-1/2 part Vanillin, or 1/6 part Ethyl Vanillin
- 0.45 mg (per 4 oz. bar) Thiamin Hydrochloride
The latter is a synthetic B1 vitamin. Although the ration is to replace just a missed meal or so, it was found feasible to fortify the ration with any vitamin possible. It was found that only the B1 vitamin would not deteriorate or affect the chocolate. (The B1 amount is sometimes labeled as 150 I.U. on the 4 oz. bar.)
Early calculations place the calorific contents for one 4 ounce bar at 600 calories. Strangely a D ration in the collection has only 448 calories labeled on the box.
The size of the 4 ounce bar is given as 3 13/16" long, 2 1/8" wide and 3/4" high (approx. 97 x 54 x 19 mm). The bar had 1/8" deep grooves in its top surface dividing the bar in 6 equal parts. The sides having a slight slope and the ends being rounded at the top.
A 2 ounce bar was also developed for use with other rations. It was made with the same formula, but with different dimensions. The early 2 ounce bar was just a 4 ounce bar cut lengthwise in two. But this proved too long to fit conveniently in the K ration box without tearing the cellophane bag. In 1943 the size was standardized as 3 1/8" long, 1 9/32" wide and 13/16" high (approx. 80 x 33 x 20 mm). This bar was divided by two 1/8" grooves across. Even a 1 ounce bar was produced in half the hight of the 2 ounce bar for use as a candy component in other rations. This bar has three serrations.
Now that a palatable emergency ration was developed the next problem was how to package it. Early directions instructed an aluminum wrapping with a paper label wrapped around the bar.
With the war looming, aluminum foil became a critical material. Another solution needed to be found to pack the D ration. The best solution was to pack a single bar in a cellophane bag that was inserted in a synthetic wax coated cardboard box. No critical material was used, yet offered adequate protection against moister and (poison) gas contamination, and was light to carry and easy to open. On one panel of this box were printed the instructions and ingredients. The instructions warned that the bar should be eaten slowly because it was found that when eaten too fast it could cause stomach ache, it also suggested that the bar could be crumbled into boiling water to make a hot cocoa drink. Furthermore it stated the company who packaged or manufactured the bar.
Complaints from the battle front were received that the bars were sometimes being thrown away because the chocolate had whitened on the surface (blooming). Mid 1943 the label carried the warning that the blooming didn't affect the eating qualities of the bar.
The 2 ounce and the 4 ounce bar packaging carried the following addition: "Storage conditions may cause the surface of the bar to whiten. This does not affect its eating quality."
In February 1944 a directive was issued that the back panel should read a warning against malaria:
"NOTICE: Mosquito bites cause malaria.
If you are in a malaria zone, keep your shirt on and your sleeves rolled down. Use mosquito repellent out of doors between sunset and sunrise."
These warnings give some time frame of production. In May 1943 the U.S. Army changed all ration nomenclatures from "U.S. Army Field Ration …" to the "Ration, Type …" So the D-bar became officially the Ration, Type D. This change was not always acted upon by all contractors:
Upon request by the USAAF a box containing 3 ration bars was developed. This box was carried in the Type B-2 Emergency Jungle Parachute Back Pad. Three cellophane packed D-bars were placed next to each other with the middle one placed upside down so that the beveled sides fit parallel against each other. This box was also coated with a synthetic wax.
The Marine Corps also showed interest in this new emergency ration and early in the war these bars for the Corps were packed in cartons labeled: U.S. Marine Corps (or U.S.M.C.) Field Ration D instead of the usual U.S. Army Field Ration D.
Twelve cartons containing a single bar were placed in a cardboard box, and twelve of these boxes were placed in a wooden crate for shipment. Or eight cartons with three bars were placed in a box totaling 24 bars, six of these boxes were placed in a wooden crate for shipment. Both crates containing a total of 144 bars.
The individual cartons were sometimes referred to as inner cartons and the cardboard box was referred to as the outer carton, or master carton. (A little confusing since the K rations also came in an inner and outer box.) The outer box was of heavy quality cardboard, or of lesser quality wax coated cardboard.
In 1944 the tin shortage became less and in the fall of 1944 it was decided that twelve single bars were to be packed in a rectangular can for overseas shipment. Twelve cans were packed in a wooden crate. The single bars only needed to be cellophane packed when placed in a can, but the cellophane then was to be printed with the same information as printed on the cartons previously used. (If the bars were still being packed in cartons the cellophane was not to be printed.)