Q. -- Please explain why there were different units called the 5th Kentucky Infantry, and how the 9th Kentucky Infantry fits into this.A. -- There were really two "5th Kentucky Infantry" regiments in Confederate service ... both ended up serving in the Orphan Brigade ... and this led to quite a bit of confusion, then and now (actually, there were four 5th Kentucky Infantry regiments, but three of them were more-or-less the same unit). When the Brigade was organized in late 1861, it contained a regiment under the command of Col. Thomas Hunt, numbered the 5th. However, unknown to the Orphans, another regiment in Eastern Kentucky had also formed as the 5th Kentucky, and since this regiment had perfected its organization first, the Confederate War Department redesignated Hunt's regiment as the 9th Kentucky in October 1862. To confuse the issue even further, the Eastern Kentucky 5th Kentucky Infantry (reorganized from the original unit) joined the Orphans in November 1863, and served with them through the remainder of the war.
Most postwar writings show Hunt's regiment as the 9th Kentucky, to minimize confusion (Thompson's Brigade histories are written this way, and the reports that appeared in the Official Records were also changed to reflect Hunt's regiment as the 9th, even during the period when they were called the 5th). However, it is still possible today to find period manuscript sources that refer to Hunt's regiment as the 5th Kentucky (some of these sources also refer to Col. John W. Caldwell, who succeeded Col. Hunt in April 1863, and who had often acted in command of the regiment previously).
Throughout this page, we will use the designation "9th Kentucky Infantry" for Col. Thomas Hunt's regiment, and "5th Kentucky Infantry" refers to Col. Hiram Hawkins' regiment, which joined the Orphan Brigade in November 1863.
http://www.rootsweb.ancestry.com/~orphanhm/faqs.htm
To summarize, the regiment which fought at Perryville was Col. Hunt's 5th/9th Kentucky Regiment. Col. Hawkins' 5th Kentucky Regiment which joined the Orphan Brigade late in 1863 was mounted with the rest of the brigade during 1864. The title "Mounted Infantry" was applied by the U.S. War Department many years after the war. It leads people to suppose that this command organized as 'mounted infantry' and served throughout the war as such. Of course that's not true.