A simply excellent overview of these events, unknown to many Americans, and not fully understood by many who do know.
First, ignore the number of 1- and 2-star reviews. If this is like Amazon, every one is nothing other than Mormon apologetics, especially over the fact that Bagley and Bigler have demonstrated Brigham Young's direct connection to the Mountain Meadows Massacre.
And, that's one of the key points of this book. Despite being nowhere near enough population for statehood, Young was determined to have either that or independence, preferring independence, and force the US government's hand on the matter. The massacre was meant to send a message to Washington that Young as Indian agent "couldn't" control Indians (hint, hint, read between the lines, President Buchanan). And, if that wasn't enough of a message, then he'd cut California off from the rest of the Union.
This despite Utah still having a largely-barter theocracy that couldn't afford a long confrontation.
Fortunately, the "first Civil War" ended without bloodshed. Unfortunately, a pliant governor to replace Young, and the removal of the Army soon thereafter, let Mormons whitewash Mountain Meadows, and play down other incidents of the last two years before fall 1857. The result is reflected in things like the propagandistic negative reviews here.