Mid-40's was not decrepit, but was not considered to be military age, at least early in the war. The Confederate Conscription Act of 1862 established eligibility for military service between the ages of 18 and 35. Men over 35 were entitled to a discharge (subject to some other criteria) and thousands of older Confederate soldiers were discharged as "non-conscripts" in the summer of 1862. As the war dragged on, however, the upper age limit was gradually modified upwards. By 1864, the upper age limit was set at 50. Of course, rules are made to be broken, and by the end of the war there were some Confederate soldiers well over 50 years old.