The Bear River Massacre was an attack by around 200 US soldiers that killed an estimated 250 to 400 children, women, and men at a Shoshone winter encampment on January 29, 1863.

[a] The establishment of the California and Oregon Trails, as well as the founding of Salt Lake City in 1847, brought the Shoshone people into regular contact with white colonists moving westward.

By 1856, European Americans had established their first permanent settlements and farms in Cache Valley, starting at Wellsville, Utah, and gradually moving northward.

[11]: 33 Brigham Young declared the policy that Mormon settlers should establish friendly relations with the surrounding American Indian tribes.

David H. Burr, Surveyor General of the Territory of Utah, wrote in 1856 that the local Shoshone Indians reported that the Mormons used so much of the Cache Valley's resources that the once abundant game no longer appeared.

[2]: 159  Soon, miners created a migration and supply trail right through the middle of Cache Valley, between this mining camp and Salt Lake City.

[16]: 78 When the American Civil War began in 1861, President Abraham Lincoln was concerned that California, which had just recently become a state, would be cut off from the rest of the Union.

[16]: 48  Neither Lincoln nor the U.S. War Department quite trusted the Mormons of the Utah Territory to remain loyal to the Union, despite their leader Young's telegrams and assurances.

[2]: 94 Col. Patrick Edward Connor[17] was put in command of the 3rd California Volunteer Infantry Regiment and ordered to move his men to Utah, to protect the Overland Mail Route and keep peace in the region.

These incidents were related to broad struggles between indigenous peoples and European-American settlers over almost the entire United States west of the Mississippi River.

Within a few days, the Shoshone retaliated by killing a couple of young men of the Merrill family gathering wood in the nearby canyon.

A girl of only five years old had her ears cut off, her eyes gouged out, both legs amputated at the knees, and by all appearances, was made to walk on her stumps.

[2]: 116 [21] As a direct result of this attack, the Army established a military fort near the present location of Boise, Idaho, along the migrant trail.

[2]: 117 Zachias Van Ornum, Alexis' brother, heard from a relative on the Oregon Trail that a small white boy of his missing nephew Reuben's age was being held by a group of Northwestern Shoshone, likely to be in Cache Valley.

[22]: 81  Van Ornum gathered a small group of friends and traveled to Salt Lake City to get help from the territorial government.

Col. Connor agreed and sent a detachment of cavalry under the command of Major Edward McGarry to Cache Valley to rendezvous with Van Ornum near the town of Providence, Utah.

After a confrontation between Bear Hunter, some warriors from his band, and nearly 70 members of the Cache Valley militia, the settlers donated two cows and some flour as the "best and cheapest policy" as compensation.

Arriving in Salt Lake City, Conover told a reporter the Shoshone were "determined to avenge the blood of their comrades" killed by Major McGarry and his soldiers.

He said the Shoshone intended to "kill every white man they should meet on the north side of the Bear River, till they should be fully avenged.

He reported to the U.S. War Department before the engagement: I have the honor to report that from information received from various sources of the encampment of a large body of Indians on Bear River, in Utah Territory, 140 miles north of this point, who had settlements in this valley to the Beaver Head mines, east of the Rocky Mountains, and being satisfied that they were a part of the same band who had been murdering emigrants on the Overland Mail Route for the last fifteen years, and the principal actors and leaders in the horrid massacres of the past summer, I determined, although the season was unfavorable to an expedition in consequence of the cold weather and deep snow, to chastise them if possible.

His main concern was to avoid the problems that McGarry had faced in the earlier action, where the Shoshone had moved and scattered even before his troops could arrive.

George A. Smith, in the official Journal History of the LDS Church, wrote: It is said that Col. Connor is determined to exterminate the Indians who have been killing the Emigrants on the route to the Gold Mines in Washington Territory.

If the present expedition copies the doings of the other that preceded it, it will result in catching some friendly Indians, murdering them, and letting the guilty scamps remain undisturbed in their mountain haunts.

....We wish this community rid of all such parties, and if Col. Connor be successful in reaching that bastard class of humans who play with the lives of the peaceable and law-abiding citizens in this way, we shall be pleased to acknowledge our obligations.

[16]: 79 [24]The first group to leave Fort Douglas was forty men of Company K, 3rd Regiment California Volunteer Infantry, commanded by Captain Samuel W. Hoyt, accompanied by 15 baggage wagons and two "mountain howitzers", totaling 80 soldiers.

[citation needed] Col. Connor met up with Hoyt that evening as well, with orders to begin moving at about 1:00 am the next morning for a surprise attack, but an attempt to get a local settler to act as a scout for the immediate area led the actual advance to wait until 3:00 am.

[2]: 181 Most of the firearms that the Shoshone had at the time of the attack had been captured in minor skirmishes, traded from fur trappers, white settlers, and other Native American tribal groups, or simply antiques that had been handed down from one generation to another over the years.

[1][page needed] He reported capturing 175 horses and some arms, and destroying 70 lodges and a large quantity of stored wheat in winter supplies.

[16]: 86  Connor campaigned against Native Americans in the West for the remainder of the U.S. Civil War, leading the Powder River Expedition against the Sioux and Cheyenne.

[40] This documentary sets out a detailed account of the massacre and Connor’s role in the dispossession and killing of first nation Americans in modern day Utah, Idaho and Colorado.