It seems strange that Tiller would be seeking an appoinment as a cadet at this point. Why are he and Captain Hart in Houston Texas in February 1864?

According to his application, Tller, was captured at Arkansas Post in Janury 1863, but escaped from the transports moving the prisioners north and returned to service with General Holmes and commanded a battery at Helena.

I wounder appointment as a cadet migh be a way for a supernummary officer to return to a paid status?

Houston, Texas
Feby 26th 1864
Genl. S. Cooper, Adjt Genl
I have the honor to make an application for an appointment as “Cadet: in the Confederate States Army. My birthright is Mo, from which I was driven and sought refuge with the army in Ark, which State I propose to make my home. I entered the service in Reiff’s unattached Cavalry Compy, May 1861, shortly afterwards joined Harts Battery Light Artillery, in which Company I remained until I was made a prisoner of War at the Arkansas Post, jany 11, 1863. Escaped a Memphis, and reported to Lt. Genl Holmes, was put in command of a battery, which I commanded at Helena Ark July 4, 1863, In Nov was ordered to report with Capt Hart. To Genl Magruder Comdg. Dist of Tex. I am prepare to stand an examination in either Arty or Ord; and to my deportment both military and moral, I must respectfully refer you to the recommendation s of the undersigned officers of whom I have the honor to be acquainted and whom I have been associated during the war; am 19 years of age, am perfectly healthy.
General I have the honor to be Sir very respectfully you obt Servt,
W. t. Tiller
Lieut Arty.

Feby 25, 1864
Genl. Lieut. Tiller entered my company as a private Aug/61, his conduct and deportment as a Soldier; though but 16 years of age, caused me to promote him. In the non com grade, to a gunner, his conduct at the memorable battle of “Elk Horn” and other trival engagements promoted him to a Sergeant and afterwards to Order Sergt from Ord Sergt to Lieut comdg Section. For my unbounded confidence in him and pursuant to an order from Genl Churchill while at the Arkansas Post, I sent Lt tiller with his section (Rifled) down to operate on the Mis River again the enemy transports during which expedition he captured and brought safely up the Arks River to the Post the Transport “Blew Wing” with her valuable cargo. I cannot highly commend him for his gallant conduct at the battle of Arkansas Post, Jany 11, 1863, in which he displayed so much courage and cool in commanding his section which did fearful execution in the enemy’s ranks. I therefore recommend him to your kind offices , for the appointment for which he applies and so meritoriously deserves. The lieut is a you man of no disputation whatsoever, and as to his capabilities, as an officer, no one has reason to doubt. I have the honor to be genl you most obt Sevt.
W. Hart, Capt Arty