The 5th cavalry was composed of companies from different states and can scarcely be called an Iowa regiment. It was originally known as the “Curtis Horse,” organized by order of Gen. Fremont. Before the close of the war there were consolidated with it two companies of the 5th IA infantry, the fragments that were left of that regiment after a glorious career.
Source: The Union Army, vol. 4
By the end of November it was again mounted and equipped as cavalry and was at the front, disputing the march of Hood’s army into Tennessee. Its first important conflict was at Duck river, after which the regiment fell back with the army to Nashville, and when the great battle before that city was fought it took part at the extreme right where it suffered but little. In the pursuit of Hood, which nearly annihilated his whole army, the regiment was very active, repeatedly overtaking and engaging his cavalry, with some loss.