This link will give you a good understanding of the environment that motivated the radical change in how both Daniel and Revelation were reinterpreted:
https://www.linkedin.com/pulse/what-happened-we-seeing-eyes-see-peter-hofmann-u1o4c
Gabriel first appeared to Daniel in Chapter 9 to message Daniel and the entire world then and now that a Glorious Appearance would happen (Dan. 9:27) that would end the need for Temple offerings and sacrifices and would be the New Covenant of Grace:
The big question to the Church is; Was Darby a pawn of nefarious forces or was he just a willing intellectual trying to modernize Christian thinking? The author realizes that this subject may seem dry or overly theological, but it is not. This is a mystery-thriller involving real historical figures and the failure of stoic leaders to uphold the integrity of the Scripture. The error or ruse has affected the core message and timing of Biblical Prophecy, and a supernatural power may have been responsible. Is a supernatural conflict taking place now as wars rage and as we dive into a Biblical intrigue between angels, demons, and humans who have fallen for man’s philosophies, religious constraints, and denominational myopia? This book focuses on 3 epic moments in history:
1) The Prophet Daniel on his knees in sackcloth being visited by Archangel Gabriel—“you are greatly beloved, Daniel.”2) The Appearance of the Messiah 483 years later and 3.5 years earlier than what has become accepted dogma in most seminaries – due to tainted calculations done by an obscure man named Harold Darby in mid-19th century. He eliminated God’s 360-Day year and redefined theology and the timing of prophetic events. All this “discovery” by Darby happened during an enlightenment period in his area of Europe that also saw the rise of Marxism, Materialism and Evolution,3) After those 3.5 years of ministry, the Messiah fulfills the Message given to Daniel by Gabriel as recorded in Daniel 9:27.
Original Hebrew shows that “He” from verse 26 is the “Anointed One” and not the plural “people of the commander” which Darby insists is a future Anti-Christ who makes a covenant with Israel. A new book is exposing a Truth hidden by years of dogma and confusion: that Darby was influenced by the intellectual movement in his time and the motive may have been to appease the logic of science (using 365-day solar years verses the non-scientific 360-Day years) and thus glorify the “new practical thinking spreading in Europe and America” verses God.