Armageddon is a corruption of Har Megiddo, or Mount Megiddo (more accurately Tel Megiddo, a tel being a mound built up by successive communities built one upon the ruins of the previous one). Megiddo is a site in the southern Jezreel valley in northern Israel where there had been many battles in ancient times. We visited there in l965 at which time they were excavating ruins of fortifications built during the reign of King Solomon.I had read up on Har Megiddo while researching the column, and I didn't at any point believe that the site was in the city of Jerusalem, so I can only surmise that I meant to write "Israel" and somehow substituted city for country. Is this what linguist Geoff Nunberg calls a thinko, or something even less explicable, just a dumb-o? Apologies to all, especially the OED.
[Update, 12:33 p.m.: Online version now fixed, thanks to my colleagues at boston.com. I love the 21st century.]