Caisson Platoon Soldiers assigned to the Caisson Platoon of the 3rd U.S. Infantry Regiment, known as the "Old Guard," participate in ceremony support for Military Day at the National Grand Prix Upperville Colt and Horse Show in Upperville, Va., June 8, 2019. SHARE: Download: Full Size (1.87 MB) Tags: Army, military units Credit: Army Sgt. Jacob Holmes VIRIN: 190608-A-GA562-026Y.JPG Photo Gallery