Armageddon
Whether Armageddon names a place for a real battle or stands for the final conflict.
Revelation 16:12-16
12The sixth poured out his bowl on the great river, the Euphrates. Its water was dried up, that the way might be prepared for the kings that come from the sunrise.
13I saw coming out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet, three unclean spirits, something like frogs;
14for they are spirits of demons, performing signs; which go out to the kings of the whole inhabited earth, to gather them together for the war of that great day of God, the Almighty.
15“Behold, I come like a thief. Blessed is he who watches, and keeps his clothes, so that he doesn’t walk naked, and they see his shame.”
16He gathered them together into the place which is called in Hebrew, “Megiddo”.
What each tradition says
Rabbinic / Midrashic
The Jewish Encyclopedia reads the sixth vial as poured upon the great Euphrates, which dries up to prepare the way for the kings of the East, the Parthians. It says they gather in Armageddon, identified as 'Ir Magdiel, a symbolic name for Rome. It also states that Revelation 16:13-15 is an interpolation.
Jewish Encyclopedia (1905), article "Revelation (Book of)", The Jewish Encyclopedia (Funk & Wagnalls, 1901-1906) — "Vision of the Seven Plagues" (on xvi. 12-16)
Patristic
Bede says he gathered them to battle, and they compassed the camp of the saints and the chosen city, that is, the Church. The name may also be understood as the seat of the devil, who in the man of perdition will resume his former plotting, for Hermagedon is interpreted "rising up together to former things" or "the round mountain."
Bede (the Venerable), The Explanation of the Apocalypse, trans. E. Marshall (1878) — Book III, on Revelation 16:16 ("Hermagedon")
Catholic
Haydock, citing Challoner, explains the name Armagedon as meaning “the hill of robbers.” This is the definition Challoner’s note gives for the term.
George Leo Haydock (citing Challoner), George Haydock's Catholic Bible Commentary (1859) — On Revelation 16:16 (Challoner's note)
Orthodox
No sourced position found. Checked CCEL NPNF (Cyril of Jerusalem npnf207, Gregory of Nyssa npnf205; ANF vol. 7 — the Revelation commentary there is the Latin Victorinus) and searched the CCEL corpus: no Greek father's text covers Rev 16; archive.org's Andrew of Caesarea and Oecumenius are modern copyrighted translations (lending-restricted). No public-domain Orthodox statement on Rev 16:12-16 found.
Reformed / Protestant
Matthew Henry identifies the field of battle as a place called Armageddon. He notes that some say this is the mount of Megiddo, near which, by a stream issuing from there, Barak overcame Sisera and all the kings in alliance with him, as in Judges 5:19.
Matthew Henry, An Exposition of the Old and New Testament (Matthew Henry's Commentary), vol. VI (Acts to Revelation) — On Revelation 16:16 ("The field of battle")
Evangelical
John Wesley explains that Armageddon is Mageddon, or Megiddo, frequently mentioned in the Old Testament. He says Armageddon signifies the city or the mountain of Megiddo, to which the valley of Megiddo adjoined.
John Wesley, John Wesley's Explanatory Notes on the New Testament — On Revelation 16:16