43rd Regiment, Illinois Infantry
The 43rd Regiment, Illinois Infantry was organized at Camp Butler, Illinois, and mustered in October 12, 1861. It mustered out November 30 and discharged at Camp Butler, Illinois, December 14, 1865. 
Companies in this Regiment with County of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first.
The following counties of origin are taken from the Adjutant General's Report, found on the Illinois Civil War Rosters web site. Roster pages are from the same report found on the Internet Archives web site. The rosters show the men who served in each regiment, their residences, dates of enlistment and mustering out, and other remarks.
Company F - many men from assorted counties - Roster, vol. 3, pages 257-260.
Company I - many men from the state of Ohio - Roster, vol. 3, pages 266-268.
Unassigned Recruits - Roster, vol. 3, pages 271-272.
Unassigned Drafted and Substitute Recruits - Roster, vol. 3, pages 272-273.
43rd Consolidated Infantry Regiment - Roster, vol. 3, pages 278-295 - Includes Companies A-K plus Unassigned Recruits.
- Beginning United States Civil War Research gives steps for finding information about a Civil War soldier. It covers the major records that should be used. Additional records are described in ‘Illinois in the Civil War’ and ‘United States Civil War, 1861 to 1865’ (see below).
- National Park Service, The Civil War Soldiers and Sailors System, is searchable by soldier's name and state. It contains basic facts about soldiers on both sides of the Civil War, a list of regiments, descriptions of significant battles, sources of the information, and suggestions for where to find additional information.
- Illinois in the Civil War describes many Confederate and Union sources, specifically for Illinois, and how to find them.. These include compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.
- United States Civil War, 1861 to 1865 describes and explains United States and Confederate States records, rather than state records, and how to find them. These include veterans’ censuses, compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.
- Illinois Civil War Rosters from the Adjutant General's Report, 43rd Regiment (accessed 10 May 2011) includes rosters of all the regiments and information on the different companies in each regiment.
- Illinois State Archives - Illinois Civil War Muster and Descriptive Rolls Database (accessed 14 June 2011). Search by residence, unit, regiment, company or soldier.
- National Park Service, The Civil War Soldiers and Sailors System, (accessed 10 May 2011).