Coal and petroleum represent stored sunlight energy that arrived on our planet for many millions of years, all the while being harvested by photosynthetic plants and microorganisms. The discovery of coal and oil deposits and the development of methods to exploit these resources on a large scale have led to a tremendous increase in the rate of technological and scientific developments of human societies in the last couple of hundred years. While many of these advances have resulted in great improvements of human life, others, however, have increased the ability of humans to wage war on one another with substantially greater lethal outcomes. Because of the essential roles of these materials for the construction of weapons and for the conduct of war itself, control of the land where these sources are found became a major goal of war operations, and this situation continues to this day, in particular with respect to oil.