1799 : the beginning of the time of the end, 115 years

Studies in the Scriptures, Volume III — Thy Kingdom Come (1891 edition):

Studies in the Scriptures III - Thy Kingdom Come - Edition 1911 :

The Harp of God, 1921 :

Creation, 1927 :

A period of one hundred and fifteen (115) years :

The Watchtower :

Studies in the Scriptures IV - Battle of Armageddon :

The fact is that the entire Gospel age has been a period of tribulation referred to in Matt. 24:9-12, and now in verse 29. (1) The early Church was persecuted by civil Rome, while later, when Papal Rome got control, all who refused to approve her abominations were persecuted by her (Jezebel) directly, or indirectly by the civil powers to which she was wedded (Ahab). And they were given into her power, and she wore out the saints of the Most High for a time, times and a half time - 1260 years - until A.D. 1799. And this long persecution, in which 'many were purified and made white and tried,' and in which the Mother of Harlots was 'drunk with the blood of the saints and the martyrs of Jesus' (Rev. 17:6) ended as we have already shown, practically in 1776 and actually in 1799 when the Pope and his authority were humiliated before the World.

Source : Studies in the Scriptures IV - Battle of Armageddon page 584