The phrase “after this” refers to what the Lord had shown John in Revelation 17. That chapter had detailed the alliance between Babylon (“mother of prostitutes,” Revelation 17:5) with the beast (the dragon’s sidekick, Revelation 13:1) plus the kings of the world (including presidents, premiers, prime ministers, among other titles) plus their horns (i.e., the power brokers). United in purpose, this alliance turned to make war on the victorious Lamb of Calvary (Revelation 13:13)—the moment in the chapter when the suspense had risen to its maximum (as the saints await breathlessly the outcome of the battle). But “the Lamb will conquer them, for he is Lord of lords and King of kings,” and the result is that the alliance turns on the prostitute and leaves her desolate and naked, and devoured and burned. As Revelation 14:8 had announced, “Fallen, fallen is Babylon the Great.” After John had seen those things, the Lord showed him the material of Revelation 18:1–3. The inference is that the present vision is directly connected to the previous.
1 After this I saw another angel coming down from heaven, having great authority, and the earth was made bright with his glory.