At daybreak, General Joseph Hooker's First Corps, approximately 8,000 men, advanced south through the Cornfield, where opposing battle lines opened tremendous fire on each other. Initially stopped by heavy musketry, Hooker's men regrouped and began pushing General Stonewall Jackson's men back as casualties on both sides quickly escalated. At 7:00 a.m., General John Bell Hood's Confederate Division of about 2,000 men, waiting behind the Dunker Church, was called into battle by Jackson and drove north, forcing the First Corps back across the Cornfield. General Lee then ordered troops from General D.H. Hill's command at the Sunken Road to move north into the Cornfield, and some of these regiments attacked to the field's northern edge before being crushed by the arrival of the Union Twelfth Corps. At 8:00 a.m., General Joseph Mansfield's Twelfth Corps, more than 7,000 strong, arrived and drove back Hood's men and the Confederate reinforcements from the Sunken Road, but Mansfield fell mortally wounded and General Alpheus Williams took command. At about 9:00 a.m., after a short lull, most Confederates on the north end of the battlefield retreated to the West Woods. Almost 8,000 Union and Confederate soldiers had been killed or wounded in and around the Cornfield. Just west of the Cornfield, Battery B, 4th United States Artillery moved forward with the initial Union attack and came under intense fire from Jackson's men. Its fifteen-year-old bugler, Johnny Cook, helped load and fire the cannon as other cannoneers were shot down around him and later received the Medal of Honor for his bravery. In the Cornfield, the First Texas Infantry of Hood's Division suffered more than 82 percent killed and wounded, the highest percentage for any Confederate regiment in the Civil War, and also lost a flag presented by Confederate President Jefferson Davis in Richmond, with a star made from the regimental commander's wife's wedding dress. Fighting here lasted from about 5:30 a.m. to 9:00 a.m., involved about 15,000 Union soldiers and 12,000 Confederates, and caused about 4,200 Union and 4,000 Confederate killed, wounded, and missing.
