Grant used Upton's assault technique on a much larger scale on May 12 when he ordered the 15,000 men of Maj. Gen. Winfield Scott Hancock's corps to assault the Mule Shoe. Hancock was initially successful, but the Confederate leadership rallied and repulsed his incursion. Attacks by Maj. Gen. Horatio Wright on the western edge of the Mule Shoe, which became known as the "Bloody Angle", involved almost 24 hours of desperate hand-to-hand fighting, some of the most intense of the Civil War. Supporting attacks by Warren and by Maj. Gen. Ambrose Burnside were unsuccessful.