What is the White Horse Prophecy?

It's a prophecy Joseph Smith[19] allegedly gave on or about May 7, 1843.[20] The prophecy was an elaborate apocalyptic vision that describes global turmoil and war and used symbolic colored horses (white, pale, red, and black) to represent different elements of the vision.[21]

It also referenced the idea that the U.S. Constitution will "hang by a thread"[22] though Joseph Smith reportedly taught this idea several years before the appearance of the White Horse Prophecy.[23]