Iowa recruited a regiment of men over the age of 45 called the “graybeards,” officially known as the 37th Iowa Infantry Regiment. They served from October 1862 until May 1865. The average age was 57, with more than 100 of the men in their sixties. It was a unique unit, with no other like it in the Union army. The Secretary of War gave permission for their enlistment, requiring that they serve only in guard and garrison duty. Many of these men were veterans of the Mexican War or other conflicts, but were too old for the rigors of combat and long marches. About 1,300 of their sons and grandsons served in the Union army.
One of its members was Charles King, who was 81 years old in 1863. He claimed to be the father of 21 children. Stephen Shellady was a private and a sergeant-major—he was 61 years old and a former Speaker of the Iowa House of Representatives. This unit completed guard duty in locations such as St. Louis, Cincinnati, Memphis, and Rock Island. They also protected trains carrying supplies to Mississippi. In Tennessee rebel guerillas attacked the one they were guarding. The old frontiersmen returned shot for shot. Two men were killed in this incident. Less than ten of the graybeards died or were wounded during the war; between 134 to 145 died from disease.