If you're refering to Jimmy Brownlow's act of "Naked Agression" that story is recounted at the interative center at Kennesaw,Georgia.

Headquarters First Cavalry Division

Department of the Cumberland

July 9th 1864
General:

…Brownlow performed one of his characteristic feats today. I had ordered a detachment to cross at Cochran's Ford. It was deep and he took them over naked, nothing but guns, cartridge-boxes and hats. They drove the enemy out of their rifle-pits, captured a non-commissioned officer and three men, and two boats on the other side. They would have got more but the rebels had the advantage of running through the bushes with their clothes on. It was certainly on of the funniest sights of the war, and a very successful raid for naked men to make.

Everything is quiet along the line, and citizens on the other side say the enemies were totally unprepared for a crossing on this flank.

Very respectfully, your obedient servant,

E. M. McCook

Brigadier-General Commanding Division

General, W. L. Elliott, Chief of Calvary