This was the Hershey bar custom-built for World War II
As the tensions in Europe rose ahead of World War II, the U.S. Army was worried about the next global conflict, so they commissioned one surprising bit of materiel for the war: a life-sustaining chocolate bar from Hershey that was intentionally made less tasty and more calorie-dense than other options.
It all started in 1937 when Army Capt. Paul Logan went to Hershey with a request for a pocket-sized bar that would survive high heat while providing lots of nutrients, all so paratroopers would have an emergency meal when jumping into combat.
Logan, a member of the Quartermaster Corps, met with two Hershey representatives who briefed their own superior, Milton Hershey himself. The senior brass were all in agreement that it was a good idea, so development went ahead.
The final product they came up with was the Field Ration D. It was 1-2 ounces, could survive high temperatures, and was rich in calories and some nutrients. Unfortunately, it had relatively little sweetener and a lot of cacao, giving it a bitter taste, and it was known for causing constipation. This was because the Army demanded that it "taste a little better than a boiled potato."
The initial bar was enormously successful as a weapon of war, and the War Department and Navy Department ordered millions — but Hershey didn't love the complaints about taste.
So, when the Army needed a new formulation for the tropics in 1943, the company opted to improve the taste, bringing it back up to actual candy status. The Hershey's Tropical Bar was even more heat resistant, surviving for up to an hour at 120 degrees, and was a hit with the troops. Almost 380 million of these bad boys left the Hershey factory, bound for the military.
The tropical bar contained more calories and some nutrients, especially B-1, and were made from chocolate liquor, skim milk powder, cocoa butter, powdered sugar, vanillin, and oat flour.
Vitamin B-1, Thiamin, was present in both bars because it prevented beriberi, a condition directly resulting from a B-1 deficiency that can cause nerve, heart, and muscle damage and weakness. In extreme cases, it can cause heart attacks. Troops in the tropics were at real risk of developing the disorder without supplements like the Field D Ration and the Tropical Bar.
At peak production, the factory had three floors dedicated to war production and churned out 500,000 bars per shift with three shifts per day. The high production rates earned the company a wartime production award known as the Army-Navy "E" Production Award. While that might sound like the most boring and boringly named of all military awards, it was actually a big deal.
The award came with a flag to fly over the factory and lapel pins for all employees. It was one of the best ways for a company to prove its concrete contributions to the war. A major general was sent to present the first E award to the company. Hershey received the award five times during World War II. They re-started production for the Apollo 15 astronauts and for Desert Storm.
Now, the heat-resistant chocolate is making a comeback as candy companies keep fighting for market share in hot markets like India, the Middle East, South America, and Africa.