From the Fredericksburg-Spotsylvania County Battlefields National Park:
The photo is one of a set taken at the rededication of the Irish Brigade Memorial at Fredericksburg, Virginia.
The 69th New York Infantry was one regiment in the famous Irish Brigade. On this day 150 years ago, the regiment marched up the open ground outside Fredericksburg, Virginia to assault a Confederate force well placed behind a stone wall. The 69th was, for all practical purposes, was destroyed. But their charge was so orderly and brave that observers on both sides took notice. The unit was reconstituted and reformed to fight in many other battles of the Civil War. The regiment continued to add honor to their name in both World Wars, as the 69th U.S. Infantry Regiment. On September 11, 2001, as part of the New York National Guard, it was among the first military units involved with the War on Terror.
The faces and the names may change, but the regiment lives on.