The Nauvoo Legion was unique among contemporary militias for its chain of command structure, its expanded functions of the court martial, and for operating at a city level.

In 1845 the Legion lost its official sanction as an arm of the Illinois militia, though activities continued under command of Brigham Young until the expulsion of the Latter-day Saints from the state.

Aiming to win the Mormon voting bloc, Illinois Democrats and Whigs (including Abraham Lincoln) passed a bipartisan city-state charter for Nauvoo in 1840.

[5] Historian Harold Schindler argues that the rank of Lieutenant General was granted to Smith by the State of Illinois in exchange for the Latter Day Saint vote in upcoming elections.

[2] Uncommon for the time, the power to call upon the Legion extended to the mayor of Nauvoo for municipal defense, creating a measure of independence from the county militia and state government.

[4] At the same time, it granted the court martial the legislative duty to mirror the United States army “so far as applicable” in terms of discipline, drill, uniform, rules, and regulations.

[8] Nauvoo's fourteen companies and two volunteer Mormon cohorts marched from assigned points to the temple grounds, led by Brigadier Generals William Law and Don Carlos Smith.

[8] The ceremonies included religious services, public singing, dedicatory prayers, speeches by Sidney Rigdon and Joseph Smith, after which temple architects lowered the southeast corner stone into place.

[8] This event, combined with John C. Bennett's appointment by Stephen Douglas to Master in Chancery in Hancock County, led Sharp to become a leading opponent of Joseph Smith.

[8] Additionally, older men in Nauvoo organized into a group they called the "Benjaminite Company", at one point asking the privilege of assembling with the Legion, writing to the court martial, "we still feel the spirit of seventy-six burning in our bosom, and are willing to grasp the sling and hurl the stone like David of Old.

[13] According to John Lee Allaman, "Prophet Joseph Smith and the Nauvoo City Council often used the legion as a primary agent for law and order.

"[14] On October 30, 1841, the city council ordered two companies of the Nauvoo Legion to destroy a local grog shop that was declared a public nuisance.

[8][11] During the sham battle, Bennett had asked Joseph to move to the rear of the cavalry without his usual guards; Albert Rockwood, commander of the prophet's bodyguards, objected and Smith chose a different spot.

[13] The Warsaw Signal published, "It will be but a small matter to raise volunteers enough here to raze the city of Nauvoo to the ground; if the governor of Illinois fears to deliver up Jo Smith, there will be something serious between the two states.

[13] The conference resolved to resist "peaceably if we can, but forcibly, if we must"; to call on the Missouri Governor to once again demand the extradition of Joseph Smith, and to oppose any politician from any party that would "truckle to the heads of the Mormon clan.

[13] In direct response to the Carthage conference, the citizenry of Nauvoo passed a resolution affirming Joseph Smith's role as the General, Mayor and Prophet stating, "if he has equals, he has no superiors.

[11][8] This reneged promise, along with Smith's use of the Legion to avoid extradition, became the basis for growing anti-Mormon sentiment and a bipartisan political movement to revoke the Nauvoo Charter.

"[1][2] Tensions were further exacerbated by defectors from the Church of Jesus Christ of Latter Day Saints, including Wilson Law, who was the Legion's ranking Major General.

[7][22] Forced to respond, Governor Ford called on Brigadier General John J. Hardin and Whig Major Edward D. Baker to lead five hundred volunteers from nine counties surrounding Hancock towards Nauvoo.

[22] This movement was intended to 1) disperse the wolf hunt militia, 2) attempt arrests of men connected to the killing of the Smith brothers, and 3) gather the Nauvoo Legion for military inspection.

[26] While plans for an official arsenal had been discussed since at least June 10, 1843, it was not until September 16, 1844 that Lieutenant General Brigham Young dedicated a site near the temple “to the God of the armies of Israel” and broke ground.

[13] Major General Rich stopped using his military rank and took on the title "President of the Organized Quorums of the Church of Jesus Christ of Latter-day Saints in Hancock County.

[7] In retaliation a group led by Levi Williams set fire to the Mormon settlements of Yelrome, Morley, and Lima and destroyed forty four homes.

[7] The morning of September 16, Lieutenant Frank Worrell of the nearby Carthage militia was shot and killed by Orrin Porter Rockwell after refusing an order to stop by non-Mormon Sherriff William Backenstos.

[7] Young offered 2,000 legionnaires to be commanded by Backenstos, who went through Hancock county burning "Gentile" property, and driving anti-Mormons from their homes, many of who fled across the border to Missouri and Iowa.

[7] Sometime in the late winter or spring Governor Ford stationed a small militia unit in Nauvoo to preserve order as Mormons prepared to leave the city.

[33][34] They were divided into the Spartan Band – remnant members of the Nauvoo Legion – and the Kill Devil Company – a group of non-Mormon New Citizens who were weary of anti-Mormon antagonism and hoped to defend their newly purchased property.

[33][34] Over the next five days the band of 150 withstood the siege of 1,000 men through methods such as guerrilla warfare, placing mines called a “hell's half acre”, and building up bulwarks.

[33][34] Even with the treaty terms, anti-Mormon militia members harassed the Mormons by ordering some out of the city at the point of a bayonet, entering the temple and shouting obscenities from the belltower, interfering with the burials, and searching departing wagons to remove weapons and goods.

[35] Records are sparse regarding military readiness of the Nauvoo Legion in terms of uniforms, equipment, discipline, and armaments, making an accurate state difficult to ascertain.