In 1940, the Wehrmacht troops already controlled most of Europe and the inhabitants of the island of Great Britain were desperately looking for a way to postpone the inevitable reprisals against them. To this end, the British were actively supplying weapons to numerous rebel groups across the continent. It was for them that a new tool was developed - explosive coal, as a means of sabotage at energy facilities.
At that time steam locomotives traveled on the railways, steamboats went on the seas, steam power plants worked at factories and thermal power plants. The explosion of a small but powerful charge could seriously damage boilers and nearby equipment, as well as start a fire among the fuel supplies. Throwing a fake lump of coal into the furnace or mine cart was as easy as shelling pears, and figuring out when and where it happened is an almost impossible task for the future investigation.
It was the difficulty in detecting explosives that became the most destructive factor in the new sabotage method. Even when the British got tired of carefully drilling coal and started tossing explosive charges simply covered with mud and painted, the German command was unable to protect all containers with coal from sabotage. A colossal number of soldiers were diverted for these purposes, which greatly reduced the combat readiness of the troops, therefore, sabotage effectively achieved their goal even without explosions.
American strategists learned their lesson and launched the Eldest Son project during the Vietnam War. They threw crates of defective ammunition into the jungle. Because of this, the weapons of the Vietnamese so often failed that they quarreled with its Chinese manufacturers and also began to experience serious supply problems.