The Missouri Army Argus was the newspaper of the Missouri State Guard. With the date of birth for the gentleman in question being in 1856 most likely he was a member of Co. A, 6th Missouri Volunteers, United States Army of the post Civil War era and the Spanish-American War. The fact that the card says 6th Missouri Volunteers does not necessarily mean it was of Civil War vintage. Up until just prior to WW 1 the old State Volunteer designations were still in use. With the advent of the U.S. National Guard designations just prior to WW 1 the older designations were changed to United States designations. I.E. in my home state of Virginia, the old "Stonewall" 4th Virginia Infantry became the 116th United States Infantry. The 4th Alabama became the 167th U.S. Infantry. The famed 69th New York Irish regiment became the 165th U.S. Infantry. And so on. The 6h Missouri Volunteers became the 140th U.S. Infantry of the 35th Infantry Division for WW 1. Since those days the old days state designations have not been used. The 140th Infantry still exists as a National Guard unit.