The conflict in Illinois was often rooted in the growing political and economic power of the Mormon community, concentrated in the city of [[Nauvoo, Illinois|Nauvoo]]. As the Mormon population expanded, non-Mormons in [[Hancock County, Illinois|Hancock County]], especially in the neighboring towns of [[Warsaw, Illinois|Warsaw]] and [[Carthage, Illinois|Carthage]], grew increasingly threatened by the Mormons' dominant position.<ref name=":0">{{Cite book|last= VandeCreek |first= Drew E. |contribution= Religion and Culture |title= Historical Themes |series= Lincoln/Net: Abraham Lincoln Historical Digitization Project |publisher= [[Northern Illinois University]] Libraries |contribution-url= http://lincoln.lib.niu.edu/religionculture.html |access-date= 2012-04-24}}</ref> Other sources of tension included Joseph Smith's practice of polygamy, Smith's opposition to slavery during his [[Joseph Smith 1844 presidential campaign|presidential campaign]], and the doctrine of human deification.
Tensions boiled in 1844 after Mayor Joseph Smith orderedfollowing the destruction of the anti-Mormon [[Nauvoo Expositor]] newspaper press, which had accused Smith of [[polygamy]]. Smith and the city council (made up of leaders of the church)was condemned it as a "public nuisance" andby destroyed the press.<ref>{{cite book |title=History of The Church of Jesus Christ of Latter-day Saints |date=1912 |page=432 |edition=Volume VI |quote=The Council passed an ordinance declaring the Nauvoo Expositor a nuisance,Smith and also issued an order to me to abate the saidcity nuisancecouncil. I immediately ordered the Marshall to destroy it without delay." – Joseph Smith}}</ref> In response, the [[Warsaw Signal|Warsaw newspaper]] called for a "war of extermination" against the Mormons, to be made with "powder and ball".<ref>{{Cite web |title=Warsaw Signal (1844: Jan.-June) |url=http://www.sidneyrigdon.com/dbroadhu/IL/sign1844.htm#0611 |access-date=2024-05-16 |website=www.sidneyrigdon.com}}</ref><ref>{{Cite book |last=Arrington |first=Leonard J |title=The Mormon Experience: A History of the Latter-day Saints |publisher=[[University of Illinois Press]] |year=1992 |isbn=0-394-46566-0 |edition=second |pages=62 |quote=Anti-Mormon firebrands were intemperate in their denunciation of the Mormon scum and their demands for using "powder and ball"}}</ref> Smith was arrested forAmid the destructionuproar, ofSmith thewas press,arrested and jailed in Carthage, where he and his brother Hyrum Smith were ultimately killed by a vigilante mob. After Smith's assassination, tensions between the Mormons and their opponents in Illinois escalated, culminating in a mob of about 1000 armed menvigilantes [[History of Nauvoo, Illinois#The "Mormon War in Illinois" and the Mormon Exodus|sieging Nauvoo]] in 1846.<ref>{{Cite journal |last=Herron |first=David L. |date=2024-01-01 |title=The Battle of Nauvoo |url=https://dx.doi.org/10.5406/24736031.50.1.03 |journal=Journal of Mormon History |language=en |volume=50 |issue=1 |pages=45–78 |doi=10.5406/24736031.50.1.03 |issn=0094-7342}}</ref> The Mormons eventually surrendered and were expelled from the city, crossing the Mississippi into Iowa.
In 2004, the [[Illinois House of Representatives]] unanimously passed a resolution of regret for the forced expulsion of the Mormons from Nauvoo.<ref>{{Cite web |last=Archives |first=L. A. Times |date=2004-04-08 |title=Illinois Offers Its Regrets to Mormons |url=https://www.latimes.com/archives/la-xpm-2004-apr-08-na-mormons8-story.html |access-date=2024-05-16 |website=Los Angeles Times |language=en-US}}</ref>
