Hershey’s once developed a chocolate bar for the US Army that would remain solid up to 49C (120F) and was poison gas proof but was also very bitter to prevent soldiers from eating it unless in an emergency. Troops called it “Hitler’s Secret Weapon” because of what it would do to their bowels.

Military chocolate (United States)

The first emergency chocolate ration bar commissioned by the United States Army was the Ration D, commonly known as the D ration. Army Quartermaster Colonel Paul Logan approached Hershey’s Chocolate in April 1937, and met with William Murrie, the company president, and Sam Hinkle, the chief chemist. Milton Hershey was extremely interested in the project when he was informed of the proposal, and the meeting began the first experimental production of the D ration bar.

Colonel Logan had four requirements for the D ration Bar. The bar must:

Weigh 4 ounces (113.4 g)

Be high in food energy value

Be able to withstand high temperatures

Taste “a little better than a boiled potato” (to keep soldiers from eating their emergenc… Continue Reading

Source: https://en.wikipedia.org/wiki/Military_chocolate_(United_States)#Logan_Bar_or_D_ration