The Second Battle of Petersburg, also known as the Assault on Petersburg, was fought June 15–18, 1864, at the beginning of the Richmond–Petersburg Campaign (popularly known as the Siege of Petersburg). Union forces under Lieutenant General Ulysses S. Grant and Major General George G. Meade attempted to capture Petersburg, Virginia, before General Robert E. Lee's Confederate Army of Northern Virginia could reinforce the city. The four days included repeated Union assaults against substantially smaller forces commanded by General P. G. T. Beauregard. Beauregard's strong defensive positions and poorly coordinated actions by the Union generals (notably Major General William F. "Baldy" Smith, who squandered the best opportunity for success on June 15) made up for the disparity in the sizes of the armies. By June 18, the arrival of significant reinforcements from Lee's army made further assaults impractical. The failure of the Union to defeat the Confederates in these actions resulted in the start of the ten-month Siege of Petersburg. Background The First Battle of Petersburg occurred on June 9, when Major General Benjamin Butler dispatched 4,500 troops from his Army of the James in the Bermuda Hundred area and assaulted the Dimmock Line, the outer line of earthworks protecting Petersburg. The Confederates, under the overall command of General P. G. T. Beauregard, numbered 2,500, many of whom were teenage boys and elderly men. Timid leadership on the part of Union Major General Quincy A. Gillmore and Brigadier General August Kautz led to the failure of the assault, squandering a prime opportunity to seize lightly defended Petersburg. Butler's men returned to their positions in Bermuda Hundred. After the Battle of Cold Harbor in Lieutenant General Ulysses S. Grant's 1864 Overland Campaign, the Union Army of the Potomac slipped away from General Robert E. Lee and began crossing the James River. Although the Overland Campaign's objective had been to defeat Lee's Army of Northern Virginia in a decisive battle, Grant changed his objective to be the city of Petersburg, an important rail junction that controlled the supplies leading to the Confederate capital of Richmond. Grant knew that Lee could not protect Richmond if Petersburg fell and he would be forced to battle Grant in the open. He also knew from the unsuccessful first assaults on June 9 how weak the Petersburg defenses actually were. Speed was essential to Grant's plan, requiring success before Lee realized Grant's objective and could reinforce Petersburg. Lee