| Unit Name: | 40th Regiment Illinois Volunteer Infantry |
| Dates: | August 10, 1861, to July 24, 1865 |
| Country: | United States |
| Allegiance: | Union |
| Branch: | Infantry |
| Battles: | Battle of Shiloh Siege of Vicksburg Battle of Missionary Ridge Battle of Kennesaw Mountain Siege of Atlanta Battle of Jonesborough March to the Sea |
The 40th Regiment Illinois Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War.
The 40th Illinois Infantry was organized at Springfield, Illinois and mustered into Federal service on August 10, 1861.
The regiment was mustered out on July 24, 1865.
Participated in the Battle of Shiloh, Siege of Vicksburg, Battle of Missionary Ridge, Battle of Kennesaw Mountain, Siege of Atlanta, and the March to the Sea
The regiment suffered 6 officers and 119 enlisted men who were killed in action or mortally wounded and 4 officers and 117 enlisted men who died of disease, for a total of 246 fatalities.[1]