Dennis, Elias S.
Born: 1812-12-04 Newburgh, New York
Died: 1894-12-17 Carlyle, Illinois
Flourished: Carlyle, Illinois
Dennis spent his boyhood on Long Island, migrating to Carlyle, Illinois, in 1836. In 1838, he married Mary D. Slade, widow of Congressman Charles Slade. Through this marriage, Dennis inherited a gristmill, and he also became stepfather to "Jack" Slade, who would become a notorious Western gunslinger and desperado. In August 1842, Clinton and Washington County voters elected Dennis as a Democrat to the Illinois House of Representatives, where he served until 1843. From 1846 to 1847, he represented Clinton, Perry, and Washington counties as a Democrat in the Illinois Senate. In 1850, Elias and Mary Dennis were living in Clinton County, and Elias was working as a miller. He owned real estate valued at $400. In 1857, President James Buchanan appointed Dennis U.S. marshal of the Kansas Territory. When the Civil War began, Dennis joined the Union Army. In August 1861, he became lieutenant colonel of the Thirtieth Illinois Infantry. He participated in the capture of Fort Donelson and other engagements in Tennessee, and in May, 1862, he received promotion to colonel of the Thirtieth Illinois. On November 29, he received promotion to brigadier general of volunteers, commanding a brigade in the Army of the Tennessee. Dennis saw action at the Battles of Port Gibson, Raymond, and Milliken's Bend, and in May 1863, he was placed in command of the District of Northeast Louisiana. He later held various commands in the Department of the Gulf. He earned promotion to brevet major general for his service in the capture of Mobile. Dennis mustered out of service on August 24, 1865.
Gravestone, Carlyle Cemetery, Carlyle, IL; Illinois Statewide Marriage Index, Marion County, 24 February 1838, Illinois State Archives, Springfield; U.S. Census Office, Seventh Census of the United States (1850), Clinton County, IL, 381; John Clayton, comp., The Illinois Fact Book and Historical Almanac 1673-1968 (Carbondale, Southern Illinois University Press, 1970), 210, 213; Theodore C. Pease, ed., Illinois Election Returns, 1818-1848, vol. 18 of Collections of the Illinois State Historical Library (Springfield: Illinois State Historical Library, 1923), 378, 411; Register of Officers and Agents, Civil, Military, and Naval, in the Service of the United States, on the Thirtieth September, 1857 (Washington, DC: A. O. P. Nicholson, 1857), 169; Ezra J. Warner, Generals in Blue: Lives of the Union Commanders (Baton Rouge: Louisana State University Press, 1964), 118-19; John H. Eicher and David J. Eicher, Civil War High Commands (Stanford, CA: Stanford University Press, 2001), 206.