The evangelist John of Patmos writes the Book of Revelation. Painting by Hieronymus Bosch (1505).
Armageddon [armagedd?n] also spelled as Har-Magedon in some modern English translations, is the final climactic battle (or Campaign) between God (also known as YHWH or Elohim) and the forces of righteousness, and Satan (whose name means 'adversary'), also known as the Devil. Satan will operate through the person known as the "Beast" or the Antichrist, written about in the Book of Revelation in the Christian New Testament. More generally, it can also refer to an apocalyptic catastrophe.
The word Armageddon in Scripture is known only from a single verse in the Greek New Testament[1], where it is said to be Hebrew, but it is thought to represent the Hebrew words Har Megido meaning "Hill of Megiddo" or "Valley of Megiddo". Megiddo was the location of many decisive battles in ancient times (see Battle of Megiddo).
World War I was commonly referred to in the newspapers and books of its time as "Armageddon", in addition to "the Great War"; this before the Second World War.