During its service, the battalion made a grueling march of nearly 1,950 miles from Council Bluffs, Iowa, to San Diego, California.

Veterans of the Battalion played significant roles in America's westward expansion in California, Utah, Nevada, Arizona, and other parts of the West.

At the time they enlisted, members of the Church of Jesus Christ of Latter-day Saints were seeking U.S. government aid for their migration west to the Rocky Mountains and Salt Lake Valley, despite having their previous petitions for redress of grievances denied.

Church President) sent Elder Jesse C. Little (1815-1893), to Washington, D.C., to seek assistance from the federal government for the Mormon Pioneers fleeing from the Illinois mobs.

On June 2, 1846, President James K. Polk wrote in his diary: "Col. [Stephen W.] Kearny was ... authorized to receive into service as volunteers a few hundred of the Mormons who are now on their way to California, with a view to conciliate them, attach them to our country, and prevent them from taking part against us.

"[9] On July 1, 1846, Captain James Allen, dispatched by Colonel (later Brigadier General) Stephen W. Kearny, (1794-1848), of the U.S. Army arrived at the Mormons' Mosquito Creek camp.

[11] Kane obtained Federal government permission for the refugee Mormons to occupy Pottawattamie and Omaha Indian lands along the Missouri River.

These funds were used to purchase wagons, teams, and other necessities for the American exodus (Actual wages paid over the next year to the Mormon Battalion totaled nearly $30,000).

[12] Having been forced to leave farms and homes in Nauvoo, Illinois, the Latter-day Saints were going to spend the winter on the banks of the upper Missouri River.

Young wrote a letter to the Saints living in Garden Grove in which he justified the call-up and asked for help: The President wants to do us good and secure our confidence.

There is war between Mexico and the United States, to whom California must fall a prey, and if we are the first settlers the old citizens cannot have a Hancock or Missouri pretext to mob the Saints.

[15] The Mormon Battalion was mustered into volunteer service on July 16, 1846, as part of the Army of the West under Brigadier General Stephen Kearny, a seasoned military veteran.

Newly promoted Lieutenant Colonel James Allen became ill but ordered the battalion forward along the Santa Fe Trail to overtake Kearny's Army of the West.

For the next several weeks, the Mormon soldiers came to hate "AJ" Smith and the assistant surgeon, Dr. George B. Sanderson, for their treatment of the men, and the long marches suffered across the dry plains of Kansas and New Mexico.

Because the church leaders had counseled the battalion members to avoid military medical treatment, they challenged the doctor's authority and unrest arose among the men.

Arriving in Santa Fe in October, General Kearny had dispatched Captain (brevet promotion to Lieutenant Colonel) Philip St. George Cooke, West Point class of 1827, to assume command of the Battalion.

The group acquired another guide in New Mexico – adventurer and mountain man Jean Baptiste Charbonneau, who as an infant had traveled with his mother Sacagawea across the continent with the Lewis and Clark Expedition.

The most significant service the Battalion provided in California was as a reliable unit under Cooke to reinforce General Kearny's one company of army dragoons.

During their journey over the Sierra Nevada, these men encountered one of the campsites of the Donner Party, and were ordered to bury the human remains and clean up the area.

[23] After being mustered out, Jesse D. Hunter, captain of Company B, was appointed Indian Agent for southern California by the military governor, Colonel Richard Mason.

Hunter was California's third indian agent, the first two being Johann Sutter and Mariano Vallejo, both appointed by Mason's predecessor, Stephen Kearny.