Smoke rises from U.S. gunboats, including the low-lying ironclad USS Monitor (far left), that are lobbing artillery shells at Confederate positions to cover the retreat of Union troops under Union general George B. McClellan after the Battle of Malvern Hill. The final engagement of the Seven Days' Battles took place on July 1, 1862, on Malvern Hill near the James River, and resulted in a Confederate slaughter. Union artillery massed on the hill repelled waves of Confederate attackers. "Brigade after brigade rushed at our batteries," a Union officer wrote," but the artillery … mowed them down with shrapnel, grape, and canister." Despite his advantageous position, McClellan ignored pleas to press the attack on to Richmond. Instead, McClellan ordered his army to retreat to Harrison's Landing, where it remained until late August, effectively ending the Peninsula Campaign.