{They gathered} (sun(8867)agen). Second aorist active
indicative of sunag(935c), singular (the three unclean spirits),
like ekporeuetai in verse  14 . {Har-Magedon} (Har-Maged(936e)).
John proceeds now after the interruption in verse  15 . Perhaps
"the mountains of Megiddo" though not certain. Megiddo is in the
valley of Esdraelon, and by the waters of Megiddo (the Kishon)
Israel gained a decisive victory over Sisera ( Jud 5:19 ),
celebrated in Deborah's song. See also Re 20:8ff. and Eze
39:2,4.