‘And the angel cast his sickle into the earth and gathered the vintage of the earth and cast it into the winepress, the great winepress of the wrath of God. And the winepress was trodden without the city, and there came out blood from the winepress, even to the bridles of the horses as far as a thousand and six hundred furlongs.'
John sees vividly the activity of the winepress in which the grapes are trodden and when the juice overflows the red wine flows, so that the red wine looks like blood flowing from the winepress. This takes him on in thought to the great last battle. The language is anticipatory of Revelation 19:11-21 where the heavenly horsemen go forth to judgment. It is stressing the greatness of the judgment with blood flowing for two hundred miles and deep enough to reach the horses' bridles. Sixteen hundred is the square of forty emphasising again the greatness of the judgment. The flood was on the earth forty days and forty nights (Genesis 7:12). This is a judgment far vaster than the flood.
‘Outside the city.' It was right and appropriate that it should take place outside the city for that is where Jesus was crucified (John 19:20; Hebrews 13:12). It is where that which was plagued was taken (Leviticus 14:40-41). This is Har-Magedon (Revelation 16:16 compare Revelation 19:11-21), possibly the mountain overlooking Megiddo (it means ‘the Mount of Megiddo'), where great battles were fought of old, where God discomforted Sisera (Judges 5:19; compare 2 Kings 23:29; 2 Chronicles 35:22), where God will defeat all His enemies (Revelation 19:11-21). It is symbolic of a place of mourning (Zechariah 12:11). The judgment could not take place ‘within the city' for Mount Zion is now in Heaven (Revelation 14:1), the place of the redeemed.
The picture of the winepress has in mind Isaiah 63:1-6 where the One Who speaks in righteousness, mighty to save, has trodden the winepress of God's enemies in His anger, ‘for the day of vengeance was in my heart and the year of my redeemed has come' (Isaiah 63:4). As here He is avenging the ill-treatment of His people on the those who have maltreated them. The whole picture is emphasising the awfulness of God's judgment. It is stressing that it is ‘a fearful thing to fall into the hands of the living God' (Hebrews 10:31).