The 21st Arkansas Infantry (1862–1865) was a Confederate Army infantry regiment during the American Civil War. The unit was organized from the consolidation of two understrength Arkansas units in May 1862. The unit participated in the Iuka-Corinth Campaign before becoming part of the garrison of Vicksburg Mississippi. After the capitulation of Confederate forces at Vicksburg, the 21st was paroled and exchanged back to Arkansas where it was combined with the remnants of several there Arkansas regiments to become the 1st Arkansas Consolidated Infantry Regiment (Trans-Mississippi). Another Arkansas Confederate infantry regiment, commanded by Colonel Dandridge McRae was also labeled the "21st Arkansas". To avoid confusion between two 21st Arkansas Regiments, McRae's regiment was later redesignated as the 15th (Northwest) Arkansas Infantry Regiment (making a total of three 15th Arkansas Regiments).
