A very crisp paintjob on those sons of Erin. The 28th Massachusetts was actually the largest regiment of the Irish Brigade, which also included the 63rd, 69th, 88th New York, and the 116th Pennsylvania. Their most celebrated action was at the Battle of Fredericksburg, December 13th 1862, when they charged Confederate defences on Marye's Heights At that time they were part of the 1st Division of 2nd Corps under Maj. Gen Winfield Hancock. It is reported that on that day the 28th were the only unit in the brigade to carry it's Irish colour. Ironically the defenders of the heights were also Irishmen serving in a Georgia regiment.
However, one small point, the greatcoats should actually be in sky blue wool, and not grey as depicted here. Sorry.
Faugh-a-Ballagh.