In 1857, Jame Buchanan send US troops westward to confront the Mormons on the polygamy issue and replace Brigham Young as governor of the Utah Territory.
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Actually the US troops were there to protect the US citizens who wanted to go west in peace without their wagon trains being attackec and robbed and the settlers all murdered by the Mormons...
Briggie young had made himself gov for life in his theocratic dictatorship and also king of the world as Joey Smtih had done before him and was running off any non-mormon judges and administrators that Buchanan sent to the Utah Territory..he wouldnt let them operate in Utah and he swamped the juries with friendly mormons...,
Court cases were slanted in favor of the mormon criminals
The case for the Mountain Meadows Massacre alone took 20 years to complete...
Sorry, no, the situation is actually the other way ‘round.
The Utah war started in late May, 1857, when Buchanan decided to send troops west.
Young heard of the troops’ approach by 24 July, 1857. He mustered the Nauvoo militia on 1 August, 1857. The Mountain Meadows Massacre happened on 11 September, 1857. ie, the federal troops were already nearly upon the Utah territory before the Massacre occurred.
The dispatch of troops from the east to the Utah territory contributed to the atmosphere of Mormon paranoia in which the MMM happened. Viz:
http://www.historynet.com/utah-war-us-government-versus-mormon-settlers.htm
Buchanan was ridiculed for the outcome of sending troops against the Mormons in the end of the operation.