Rather than retreat, Grant flanked Lee's army to the southeast and attempted to wedge his forces between Lee and Richmond at Spotsylvania Court House. Lee's army got to Spotsylvania first and a costly battle ensued, lasting thirteen days, with heavy casualties. On May 12, Grant attempted to break through Lee's "Muleshoe" salient guarded by Confederate artillery, resulting in one of the bloodiest assaults of the Civil War, known as the Bloody Angle. Unable to break Lee's lines, Grant again flanked the rebels to the southeast, meeting at North Anna, where a battle lasted three days.