Rev 6:10

10 They cried with a loud voice, saying, “How long, Master, the holy and true, do you not judge and avenge our blood on those who dwell on the earth?” 

how long…will You refrain from judging – the “hour” of God’s judgment is described in Rev 14:7. The martyrs who resurrected during the Reformation, are crying out, for the hour of God’s judgment. The martyrdom caused by the beast would end in 1648 with the Peace of Westphalia. In Rev 8:1, we read “there was silence in heaven for about a half an hour,” approximately 267 years (half an hour), 1/24 of the 12 hour “clock” of 6,400 years. The half an hour of silence ended with the outpouring of the holy spirit in 1917.