The Forty Days of Musa Dagh (Die vierzig Tage des Musa Dagh) is a 1933 novel by Austrian writer Franz Werfel based on true events that took place in 1915, during the second year of World War I and at the beginning of the Armenian Genocide. The novel focuses on the defense of a small community of Armenians living in the mountainous region of Hatay Province of the former Ottoman Empire—now part of present-day southern Turkey on the Mediterranean coast—as well the events in Istanbul and provincial capitals, where the Young Turkish government orchestrated the deportations, concentration camps, and massacres of the empire's Armenian citizens. This policy, as well as who bore responsibility for it, has been controversial and contested since 1915. Because of this, or perhaps in spite of it, the facts and scope of the Armenian Genocide were little known until Werfel’s novel, which entailed voluminous research and is generally accepted as based on historical events.
The novel was originally published as Die Vierzig Tage des Musa Dagh in German in November 1933. It achieved great international success and has been credited with awakening the world to the evidence of the persecution and partial destruction of the Armenian nation during World War I. The Forty Days of Musa Dagh also foreshadows the Holocaust of World War II due in part to the rise of Adolf Hitler and Nazi Germany, which paralleled the novel's creation. In 2012, the publisher David R. Godine issued a revised and expanded English translation of The Forty Days of Musa Dagh that incorporates virtually all of the material left out of Geoffrey Dunlop's 1934 translation.