Out of a darkened room at the Galerie Neue Meister looms an unspeakable scene that assaults the viewer with the intensity of a fever nightmare. The Dresden triptych, which measures four meters by two meters, was the product of three years of continuous work (between 1929 and 1932) by the artist Otto Dix and is widely considered to be his magnum opus. Under a bleak sky a solitary figure, his humanity obscured by a gasmask, surveys a bomb-ravaged quagmire littered with ruins and the gore and decaying cadavers of hundreds of fallen…