Complex sentence: However, the Confederate War Department discovered that there was already a 1st Arkansas Infantry, under Col. James Fleming Fagan's regiment, it was thus redesignated as the' 15th Arkansas Infantry', on 31 December 1861.
Split into simpler sentences: However, the Confederate War Department discovered that there was already a 1st Arkansas Infantry, under Colonel James Fleming Fagan. The 1st Regiment, Arkansasa State Troops, was thus redesignated as the 15th Arkansas Infantry Regiment, on 31 December 1861.