This chapter examines the history of fossil fuels - coal, oil, and natural gas - and their increasingly complex intertwinement with geopolitics and international relations. Fossil fuel production and use started growing in earnest in the late eighteenth century, spread to an increasing number of countries in the nineteenth century, and saw a global “great acceleration” after 1945. In the process, fossil fuels affected and were affected by international wars and other cross-border conflicts. Occasionally they were mobilized as metaphorical “energy weapons”. They also played a key role in colonialism and empire-building. At the same time, fossil fuels sparked international cooperation and brought together countries that would otherwise have found it difficult to sit around the same table. As the world enters an intense phase of renewable energy investments, it remains to be seen how and to what extent the geopolitics of fossil fuels will continue to shape global developments.