After the outbreak of the Civil War, the band held concerts to assist the war effort. Although the American Brass Band was neither the first nor only group to pair with itself with a militia or regiments, it was the first band to volunteer for active military duty, following the Rhode Island 1st Regiment to the front.  The American Brass Band served for three months and 17 days and participated in the battle of Bull Run. Musicians assisted paramedics in tending to the wounded soldiers. The band itself did not suffer any human casualties but did lose a drum, which was discovered in New Orleans a few years later. The group volunteered again a few years later with the 4th Rhode Island Regiment of Volunteers, proclaiming its service “[kept] the patriotic juices flowing and [kept] up morale.”

During Greene’s tenure with the American Brass Band, his players earned a living wage. This allowed musicians to focus their energies solely on their music, which helped to make them into one of the premier bands in all the United States. This benefited Rhode Island’s music scene; bands from throughout the country wanted to visit and perform in the Ocean State including the much-celebrated Francis Johnson Colored Band, a band composed of African American musicians that would rise to worldwide fame. Rhode Island produced many of its own bands as well, including the Newport Artillery Band and the Newport Volunteers Band. In fact, nearly every town in Rhode Island had a band that styled their music after the American Brass Band.

Greene—having lost his ability to bugle following a dental procedure—retired in December 1865.  His replacement, David Wallis Reeves, capitalized on Greene’s legacy and would eventually elevate the band to even greater heights. This included adapting a new style of play in which the music looped; this approached allowed for easier performance while marching.  Reeves also introduced more advanced compositions. The “March King” John Phillip Sousa later said of Reeves, “He made me everything I am . . . I would gladly give up all I have won if only I might have written the ‘Second Regiment March.’”

In 1887, after most members of the original band had retired from performing, the few remaining charter members collaborated with the Rhode Island Historical society to develop the American Band Veterans Association, an organization that would memorialize the band’s distinguished tradition.  Amazingly, the band is still active today and continues to perform in concerts and marches. The Providence Brigade Band, another local group that carries on the mid-nineteenth-century band music tradition in Rhode Island, has made a number of recordings (some with the American Band) of music from that period.