At around 11 a.m., Doubleday sent his reserve regiment, the 6th Wisconsin, an Iron Brigade regiment, commanded by Lt. Col. Rufus R. Dawes, north in the direction of Davis's disorganized brigade. The Wisconsin men paused at the fence along the pike and fired, which halted Davis's attack on Cutler's men and caused many of them to seek cover in the unfinished railroad cut. The 6th joined the 95th New York and the 84th New York (also known as the 14th Brooklyn), a "demi-brigade" commanded by Col. E.B. Fowler, along the pike.^[15] The three regiments charged to the railroad cut, where Davis's men were seeking cover. The majority of the 600-foot (180 m) cut was too deep to be an effective firing position—as deep as 15 feet (4.6 m).^[16] Making the situation more difficult was the absence of their overall commander, General Davis, whose location was unknown.^[17]

The men of the three regiments nevertheless faced daunting fire as they charged toward the cut. The 6th Wisconsin's American flag went down at least three times during the charge. At one point Dawes took up the fallen flag before it was seized from him by a corporal of the color guard. As the Union line neared the Confederates, its flanks became folded back and it took on the appearance of an inverted V. When the Union men reached the railroad cut, vicious hand-to-hand and bayonet fighting broke out. They were able to pour enfilading fire from both ends of the cut, and many Confederates considered surrender. Colonel Dawes took the initiative by shouting "Where is the colonel of this regiment?" Major John Blair of the 2nd Mississippi stood up and responded, "Who are you?" Dawes replied, "I command this regiment. Surrender or I will fire."^[18]

The officer replied not a word, but promptly handed me his sword, and his men, who still held them, threw down their muskets. The coolness, self possession, and discipline which held back our men from pouring a general volley saved a hundred lives of the enemy, and as my mind goes back to the fearful excitement of the moment, I marvel at it.

— Col. Rufus R. Dawes, Service with the Sixth Wisconsin Volunteers (1890, p. 169)

Despite this surrender, leaving Dawes standing awkwardly holding seven swords, the fighting continued for minutes more and numerous Confederates were able to escape back to Herr Ridge. The three Union regiments lost 390–440 of 1,184 engaged, but they had blunted Davis's attack, prevented them from striking the rear of the Iron Brigade, and so overwhelmed the Confederate brigade that it was unable to participate significantly in combat for the rest of the day.