Most soldiers were white males aged between 16 and 28. The median year of birth was 1838, so half the soldiers were 23 or older by 1861. In early 1862, the Confederate Army was allowed to disintegrate for two months following expiration of short-term enlistments. A majority of those in uniform would not re-enlist following their one-year commitment, so on April 16, 1862, the Confederate Congress enacted the first mass conscription on the North American continent. (The U.S. Congress followed a year later on March 3, 1863, with the Enrollment Act.) Rather than a universal draft, the initial program was a selective service with physical, religious, professional and industrial exemptions. These were narrowed as the war progressed. Initially substitutes were permitted, but by December 1863 these were disallowed. In September 1862 the age limit was increased from 35 to 45 and by February 1864, all men under 18 and over 45 were conscripted to form a reserve for state defense inside state borders. By March 1864, the Superintendent of Conscription reported that all across the Confederacy, every officer in constituted authority, man and woman, "engaged in opposing the enrolling officer in the execution of his duties". Although challenged in the state courts, the Confederate State Supreme Courts routinely rejected legal challenges to conscription.