text: The first heavy fighting of the campaign occurred in the Battle of Williamsburg (May 5), in which the Union troops managed some tactical victories, but the Confederates continued their withdrawal. An amphibious flanking movement to Eltham's Landing (May 7) was ineffective in cutting off the Confederate retreat. In the Battle of Drewry's Bluff (May 15), an attempt by the United States Navy to reach Richmond by way of the James River was repulsed.
  As McClellan's army reached the outskirts of Richmond, a minor battle occurred at Hanover Court House (May 27), but it was followed by a surprise attack by Johnston at the Battle of Seven Pines or Fair Oaks on May 31 and June 1. The battle was inconclusive, with heavy casualties, but it had lasting effects on the campaign. Johnston was wounded and replaced on June 1 by the more aggressive Robert E. Lee. Lee spent almost a month extending his defensive lines and organizing his Army of Northern Virginia; McClellan accommodated this by sitting passively to his front, waiting for dry weather and roads, until the start of the Seven Days. Lee, who had developed a reputation for caution early in the war, knew he had no numerical superiority over McClellan, but he planned an offensive campaign that was the first indication of the aggressive nature he would display for the remainder of the war.