It's a little known fact that Charles Taze Russel, the first president of the Watchtower Bible and Tract Society, thought 1776 had prophetic significance. He thought that year marked the end of a period of persecution.
"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..." -Studies in the Scriptures IV, page 584
Jehovah's Witnesses no longer discuss 1776 as a prophetic date in their literature. It is comical that they also had problems with dates that they discussed after the fact and didn't involve any type of prediction.