The Sixth Corps breakthrough of April 2, 1865, capped a week of fighting and maneuvering southwest of Petersburg. After the failed Confederate sortie at Fort Stedman on March 25, Union Gen. Ulysses S. Grant seized the initiative and targeted Gen. Robert E. Lee's final two supply lines, the Boydton Plank Road and the South Side Railroad. Beginning on March 29, Grant used Gen. Philip H. Sheridan's newly arrived cavalry and the Fifth and Second Corps of the Army of the Potomac in the offensive. Sheridan's horsemen occupied the Boydton Plank Road at Dinwiddie Court House on March 29 without serious opposition, while Gen. Gouverneur K. Warren's Fifth Corps pushed farther north, fought at the Lewis Farm, and aimed for the railroad beyond Lee's extended right flank. Major engagements at White Oak Road and near Dinwiddie Court House on March 31 led to the struggle for control of the railroad at Five Forks on April 1, where the Union won an overwhelming victory. Sensing that the Confederates had reached their breaking point, Grant ordered an all-out assault on Lee's line at dawn on April 2, and the Union Sixth Corps attacked across this ground that morning.