 Complete the following phrase:  Enlisting for Civil War military service during the summer of 1862, Buck enrolled on August 17 at Windsor, Connecticut, and officially mustered in as a private with Company A of the 21st Connecticut Volunteer Infantry. Assigned initially to the Unions Army of the Potomac, he and his fellow 21st Connecticut Volunteers fought in the Battle of Fredericksburg from December 1215 of that year. While engaged in Burnsides Mud March, Buck was promoted to the rank of corporal on January 20, 1863. He and his regiment then participated in the 