Following the Battle of the Wilderness, Lt. Gen. Ulysses S. Grant marched the Union Army of the Potomac toward Spotsylvania Court House. Grant hoped to clear the tangled secondary growth forest and get between Robert E. Lee and the Confederate capital at Richmond.Lee, however, managed to get ahead of the Federals and blocked the route to Spotsylvania. Fighting began on May 8, when the Union V Corps under Maj. Gen. Gouverneur K. Warren and the VI Corps under Maj. Gen. John Sedgwick engaged Confederate Maj. Gen. Richard Anderson's First Corps and Lt. Gen. Richard Ewell's Second Corps near Laurel Hill and the area east of the Brock Road. Sedgwick was killed by a Confederate sharpshooter the following day. Meanwhile, the Confederates extended their position into a salient later known as the Mule Shoe. After a failed offensive against Lee's left on the Po River, elements from the Sixth Corps struck the Mule Shoe on the evening of May 10. Led by Col. Emory Upton, the Federals achiveved a temporary breakthrough, however, they were unsupported and reinforcements arrived to plug the gap. Upton's success inspired Grant and he decided to launch another, larger assault against the salient. Early on the morning of May 12, the Union II Corps under Maj. Gen. Winfield S. Hancock smashed through the Mule Shoe. Confusion and loss of command and control allowed Lee to counterattack and buy time for a new line to be completed. Ferocious hand to hand fighting swirled around a bend in the earthworks later known as the "Bloody Angle". By dawn on May 13 the new position was ready and the Confederates abandoned the Mule Shoe. After attacks against Lee's left and center, Grant decided to shift toward the Confederate right. Fighting erupted on May 14 at Myers' Hill as the Federals attempted to gain a toehold on the south bank of the Ni River. Mother Nature finally intervened and brought a brief lull to the combat. On May 15, elements from the 23rd United States Colored Troops (USCTs) repulsed a Confederate reconaissance led by Brig. Gen. Thomas Rosser in the Union rear near Chancellorsville. This was the first time USCTs were involved in combat in Virginia. When the rain abated, Grant decided to assault Lee's line at the base of the Mule Shoe. At dawn on May 18 Union infantry moved forward only to be brought to a halt by massed Confederate artillery. Lee attempted to turn Grant's left and cut his supply lines the next day only to be pushed back at Harris Farm. Facing another stalemate, Grant decided to swing off to the south and east to pry Lee out of his communications. He set the army toward the North Anna River and a new phase of the Overland Campaign.