Thanks for the list and explanation of the various Texas regiments known as the Ninth.
However, I did not mean to imply that all the companies of the Ninth (Nichols') were from the Montgomery/Walker County areas. Only Company I was from the Montgomery area, as far as I know.
My great-grandather, James Marion McCan(n), was also in the Ninth (Nichols') but was in Company E under James Gillespie. This company apparently was recruited in Walker and Madison Counties, and there is a monument in the city of Huntsville that is dedicated to the companies which were raised by James Gillespie in the Texas Revolution and in the Civil War. (See link below for biography page of James Marion McCan.)
I have not tried to trace the other companies of the Ninth (Nichols') to their county of origin, but I think some of them were from Galveston and surrounding counties.
The men who signed up in Nichols' did so as a result of a call to arms issued to the Texas State Troops (militia) by General Paul O. Hébert in the late summer of 1861; this was in response to Lincoln's blockade of southern seaports (including Galveston) and his threat to invade.