“The period from April 1861 to August 1862 could be referred to as the “regimental band period” of the Federal Army. It was a time when hundreds of bands and thousands of bandsmen were mustered in with volunteer regiments and paid solely to furnish military music. Considered noncombatants, these regimental bandsmen generally were not required to perform duties outside of their musical responsibilities. …
“By the closing months of 1861, the Federal government had begun to experience financial difficulties caused by the war, and it soon realized that it could no longer afford the luxury of permitting volunteer regiments to have bands. …
“The major blow to regimental bands came in July of 1862 when the War Department issued General Order No. 91 directing that all regimental bandsmen be mustered out of service within 30 days. Musicians who were recruited from infantry companies to serve in bands (some bandsmen were recruited in this manner), were ordered to be transferred back to their units. Bandsmen who had been mustered in as musicians were to be discharged from the service or, with their consent, to be transferred to brigade bands.”
Excerpt from : A Pictorial History of Civil War Era Musical Instruments & Military Bands, p. 53-54.
