| 43rd Regiment Illinois Volunteer Infantry | |
|---|---|
 Illinois state flag | |
| Active | October 12, 1861, to November 30, 1865 |
| Country | United States |
| Allegiance | Union |
| Branch | Infantry |
| Engagements | Battle of Shiloh Siege of Vicksburg |
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The 43rd Regiment Illinois Volunteer Infantry, known as the "Koerner Regiment" after Gustav Körner, was an infantry regiment that served in the Union Army during the American Civil War.