I can speak to World War II; specifically American G.I.s. Chocolate was a prevalent part of the G.I. diet. They received a chocolate “Emergency Bar” with their K Rations (their daily boxed and canned meals). The Emergency Bar was also called the D Ration. This Chocolate bar contained a mix of sugar, cocoa, and other elements to make it a “High Energy” Bar. Now-in-days the bar would not be considered thoroughly high energy, like infused with caffeine and a ton of sugar, but by World War II standards, when sugar was used more sparingly the D Ration was considered an energy booster. It would be considered relatively bland, if not chalky, to today’s chocolate bars. The D Ration was made by the famous American confectionary company The Hershey Company. Later in the war, specifically because of the fighting in the Pacific Theater, the Tropical Bar was introduced by Hershey. It was essentially the same as the traditional D Ration, but more resembled a regular Hershey Chocolate Bar as we know it today (a brick of Hershey chocolate which can be broken in to smaller segments). It was designed with more sugar and other ingredients to help it withstand the humid sweltering heart of the South Pacific. Towards the end of the war the Tropical Bar started replacing the D Ration, in every theater, and became the new D Ration emergency bar. Other companies, including Mars, Inc. issued candy to soldiers as well (Mars Bars to British troops, and M&Ms to U.S. troops). The Germans also included an Ersatz chocolate bar in their rations, but by the end of the war it was mostly made up of non – Chocolate and non-organic materials and was considered pretty disgusting. The Hitler Youth and younger soldiers would get chocolate bars with their rations instead of cigarettes like the older fighting aged soldiers. Almost every nation used chocolate as a snack and ration substitute.

So now we know about the D Ration, I will elaborate further on your question. Yes, the D Ration had more of an impact than just a morale one. Many G.I.s when out on patrol or dug in somewhere could not light fires to heat their meals, and could not carry around the cumbersome K Rations boxes, but they could easily carry a large chocolate bar in a pocket, or in a rucksack. Oftentimes when out on patrol the D Ration, the Emergency Bar, was the only food that soldiers would eat – sometimes for days. The chocolate and sugar would keep them going. That was the intent of the bar by the military planners. They wanted something that a soldier could carry with him wherever and could provide an extra boost, a pep in his step, especially when hot coffee (the preferred drink of the G.I.) was unavailable.

Now of course not every G.I. loved chocolate and the D Ration, some thought it was too sweet, and others thought it was too chalky and not sweet enough. Oftentimes the troops who did not like their D Ration would trade them with non – smoking G.I.s for their 4 pack Lucky Strike Cigarettes ration (that came in the standard K Ration box). Either way, the military wanted it’s soldiers to be able to fight, and get some energy – whether it was from a high energy chocolate bar or pack of cigarettes, paired with liberal amounts of coffee.

The D Ration’s main intent was to be a food and energy supplement for combat soldiers. It was also packed in most Naval and Air personnel’s emergency bail out kits. The D Ration’s first and for most intent and application was to be able to give the soldiers a snack, or in many cases a meal, on the go, that could put an extra pep in their step. Of course many soldiers gave their extra D Rations to starving children (who going through German occupation, and probably not seeing chocolate of that quality in years, probably left tem bouncing off the walls from all the sugar). This ingratiated the G.I.s to the local populous, especially the children.