South of the pike, Archer's men were expecting an easy fight against dismounted cavalrymen and were astonished to recognize the black Hardee hats worn by the men facing them through the woods: the famous Iron Brigade, formed from regiments in the Western states of Indiana, Michigan, and Wisconsin, had a reputation as fierce, tenacious fighters. As the Confederates crossed Willoughby Run and climbed the slope into Herbst Woods, they were enveloped on their right by the longer Union line, the reverse of the situation north of the pike.^[13]

Brig. Gen. Archer was captured in the fighting, the first general officer in Robert E. Lee's army to suffer that fate. Archer was most likely positioned around the 14th Tennessee when he was captured by Private Patrick Moloney of Company G., 2nd Wisconsin, "a brave patriotic and fervent young Irishman." Archer resisted capture, but Moloney overpowered him. Moloney was killed later that day, but he received the Medal of Honor for his exploit. When Archer was taken to the rear, he encountered his former Army colleague Gen. Doubleday, who greeted him good-naturedly, "Good morning, Archer! How are you? I am glad to see you!" Archer replied, "Well, I am not glad to see you by a damn sight!"^[14]