From June 26 to July 2, the Seven Days' Battle occurred. This included the fighting at Mechanicsville and at Gaines' Mill. In these two skirmishes, Lee, after severe fighting, drove the right wing of McClellan's army under General Porter across the Chickahominy River. At Glendale, Confederate Generals James Longstreet and Ambrose Hill fought terrific hand-to-hand skirmishes with gun butts and bayonets against the rearguard of the forces under McClellan. At nightfall, the Confederates retreated to Malvern Hill. On the following day, the forces under McClellan set up infantry fire with cannon fire just preceding it at the top of the hill. As the separate Confederate detachments charged up the steep hill, they were literally mowed down by the thousands. McClellan retreated during the night to Harrison's Landing. In spite of these military maneuvers, the army under McClellan was finally forced to retreat at the end of the Seven Days' battle, and Richmond, the "City of Seven Hills," still remained in Confederate control. On August 9, as Jackson was on his way to encounter the Union General, John Pope, who had started southward, he unexpectedly met Union General Nathaniel P. Banks near Cedar Mountain (later called "Slaughter Mountain"), located just south of Culpeper. Severe fighting resulted, and the forces under Jackson had almost been annihilated when they received reinforcements which pushed the Union forces back. Since the number of casualties was extremely high during this battle, Jackson allowed Banks to bury his dead the following day. On August 30, the Union troops made a second attempt to capture Manassas. Jackson defeated Union General Pope in the Second Battle of Manassas or Second Battle of Bull Run, after destroying large quantities of his supplies. When the Confederate troops had used all their available ammunition, they used stones until reenforcements under General James Longstreet arrived. These soldiers forced the Union troops under Pope to retreat to Centerville and eventually to Alexandria. On September 5, 1862, General Lee, believing the time was suitable for invading the North, advanced across the Potomac River into Maryland. As they approached Frederick, they sang and marched to "Maryland, My Maryland" but this gesture did not result in large numbers of Marylanders joining the Confederate armed troops as they had hoped. After Jackson had successfully captured Harper's Ferry, Lee moved his remaining troops to Antietam Creek near Sharpsburg, Maryland. Severe fighting with McClellan's troops resulted and the Confederate forces in this area finally were forced to recross the Potomac River into Virginia.