Tanner became a member of the
Grand Army of the Republic (GAR) shortly after it formed. The organization was a fraternal association for military veterans who had served in Union armies during the Civil War. His fame as a disabled veteran and witness to the Lincoln assassination made him popular among GAR members, and in 1876 they elected him Commander of the New York state organization. Many attempts had been made in the previous decade to create an
old soldiers' home in the state, but none of these efforts bore any fruit. Tanner was determined to see one built by the state. He enlisted the help of the Reverend
Henry Ward Beecher, a noted
abolitionist and firebrand preacher, and held an organizing meeting in
Brooklyn which raised $13,000 ($). Tanner then criss-crossed the state numerous times, making speeches and holding rallies. Tanner's efforts were so successful that in 1879 the
New York State Legislature appropriated money for a 600-bed Soldiers' Home in
Bath, New York. Tanner was also a member of the
Union Veteran Legion, and was elected national commander of that association as well. Tanner was also active in the American Red Cross.
Clara Barton founded the organization in 1881 and led it for almost a quarter century. But by the early 1900s, Barton's leadership had devolved into a
cult of personality and the organization's finances were in severe straits. Barton was forced out, and new leadership established a more professional and bureaucratic organization. Among those elected to the Red Cross' board of directors was James Tanner. Tanner worked assiduously to win a
Congressional charter for the reorganized American Red Cross, which was granted in 1904. Tanner later served on the organization's central committee and its executive committee. ==Death==