Mars in Aries (a literal translation of the German original title, Mars im Widder) is the most widely known novel by the Austrian writer Alexander Lernet-Holenia. It was written during the winter of 1939-1940 and is about the author's combat experience during the invasion of Poland by the German Wehrmacht at the start of World War II. The novel draws its disturbing quality from an intimate interlacing of precisely described authentic combat episodes with a concept of a pervasive Otherworld that merges with our reality in a way that makes it difficult to determine whether one has already transgressed its borders. It stands in the tradition of the early 20th-century Austrian psychological novel genre of which Schnitzler's Dream Story and Perutz' The Master of the Day of Judgement are other famous examples.
As Count Wallmoden, an Austrian World War I veteran and lieutenant of the reserve, readies himself for a four-week military exercise which is scheduled to start on August 15, 1939 he experiences the first of several derealization episodes. Later, during an idle evening spent in talk with his fellow officers, as the discussion touches on the topic of spiritism, his regimental commander half-jokingly promises Wallmoden that whenever they meet he would indicate whether he is still alive or already dead because that might not be immediately apparent to a living person. During a training attack near the village of Würmla Wallmoden has an apparition of naked ghosts swirling around him. He keeps this vision to himself until much later when he reports it to a military physician, who tells him that there is nothing necessarily wrong with him, as hallucinations in the sane are not uncommon as most people believe.