The dream was that by Babylon's King Nebuchadnezzar. (Daniel 4:1-37)
He saw in the dream a great felled tree which Daniel interpreted to indicate his kingdom which would be taken for a period of seven years, and then restored [remember: Babylon was the kingdom used by God to destroy his Jewish kingdom over the earth; because of the Jews own wickedness (Deu 9:4-6)]. That dream prophecy fell in it's first fulfillment on Nebuchadnezzar, as he did loose his sanity and kingdom for 7 years, but was then restored to the throne. The prophecy had a second and greater application to the restoration of God's kingdom over earth, (Rev 21:1-4) and to the end of the Gentile times [the end of the string of secular nations that have ruled since Nebuchadnezzar: Babylon, Media-Persia, Greece, Rome, England-America]. (Luke 21:24)
Applying a formula Bible students from several denominations believed to be scriptural, to count forward from 607 when God's kingdom rule of the earth ended, they arrived at 1914 C.E. as being the year when God's rulership of the earth would be reestablished; thus beginning the eternal earthly rulership of God's Kingdom by his Christ: (1 Cor 15:12-28)