21st Illinois Infantry Regiment
| 21st Regiment Illinois Volunteer Infantry | |
|---|---|
| Active | June 28, 1861–December 16, 1865 |
| Country | United States |
| Allegiance | Union |
| Branch | Infantry |
| Engagements | |
| Commanders | |
| Notable commanders | Ulysses S. Grant |
The 21st Regiment Illinois Volunteer Infantry was a volunteer infantry regiment that served in the Union Army during the American Civil War.