"When provided as a morale boost or care package, military chocolate is often no different from normal store-bought bars in taste and composition. However, they are frequently packaged or molded differently. The World War II K ration issued in temperate climates sometimes included a bar of Hershey's commercial-formula sweet chocolate. But instead of being the typical flat thin bar, the K ration chocolate was a thick rectangular bar that was square at each end (in tropical regions, the K ration used Hershey's Tropical Bar formula)." Yep, that's what I found and tasted.
"When provided as an emergency field ration, military chocolate was very different from normal bars. Since it was provided as a quick emergency food source, officials initially outlined that it should not be a tempting treat that troops might eat before they needed it. But even as attempts to improve the flavor were made, the heat-resistant chocolate bars never received rave reviews. Emergency ration chocolate bars were made to be high in energy value, be easy to carry and to withstand high temperatures. Withstanding high temperatures was extremely important, since infantrymen would be outdoors, sometimes in tropical or desert conditions, with the bars in their pockets against their bodies. These conditions would make any normal chocolate bar melt within minutes."
What about the taste? I imagine it tasted great to the military personnel.