The 20th century was marked by two of the bloodiest global wars in history as well as numerous colonial and resource-driven military conflicts spanning from the Philippines in 1899 to the Persian Gulf in the 1990s. The First World War and its mechanized slaughter represented both the demise of the illusion of modernity as a force of progress and enlightenment and the full maturation of the Gothic mode as a literary paradigm capable of expressing that failure. Although the War Gothic has existed since the 18th century, it came into its full range and power only with the nightmarish conditions of the trenches and chemical weapons in World War One. There are several main strands of the War Gothic, including battlefield horror, focusing on injury and the destruction of the human body in combat, and psychological horror, focusing on the invisible injuries to the mind and heart, often figured as being haunted, becoming monstrous or undead. The Gothic has also been used to describe the uncanny transformations of cities, societies and landscapes under the strain and violence of wartime conditions. This chapter will focus on several key texts which represent the most important cultural work of the War Gothic, from the war poetry of the trenches to the horror fiction and cinema of the Vietnam War, ending with a quick look at the new developments in the Gothic representation of war at the end of the 20th century.