Revelation 13:5

5  And there was given unto him a mouth speaking great things and blasphemies; and power was given unto him to continue forty and two months.

In the first four verses it is talking about the rise of a world empire and the verses only give us some hints of a man but the rest of the chapter primarily talks about the satanic man that is the power behind this Beast kingdom.

Again we are told that this person will be given power to continue for 3 ½ years. This period of time starts at the time Satan is cast out of heaven and indwells the world leader who has probably died and becomes incarnated by the Beast that ascends out of the pit. The Beast then kills the two prophets and desecrates the Jewish temple (this occurs at the end of the sixth trumpet). The reign on the earth by this Beast will last until Jesus defeats Him at His coming. The period of the reign of the Beast is the same 3 ½ year period when the obedient that flee from Jerusalem are under the protection of Michael in the mountains.