This is an easy answer.

Militia service has always meant short-term local service with minimal or no training, arms or uniforms. Of course that means minimal usefulness for military purposes. Military commanders preferred long-term enlistments which would allow proper training, equipment and deployment wherever and whenever needed, not just in a specific locale for a short period of time.

For this purpose the Confederate government passed a law on April 16, 1862, requiring most men between the ages of 18 and 35 to render military service for three years or the war. Eventually age limits were raised to include men as old as age 45, which took most citizens out of the militia and into the Confederate army.

After passage of the law of April 16, 1862, we rarely ever see militia commands mentioned again except for short-term emergencies.