Grand Declaration of War is the second full-length studio album by the Norwegian black metal band Mayhem, released by Necropolis Records on 6 June 2000.The album's title and some of the lyrics are taken from the writings of the German philosopher Friedrich Nietzsche, particularly his books Twilight of the Idols and The Antichrist. Nietzsche called Twilight of the Idols "a grand declaration of war" („eine grosse Kriegserklärung“).