Pamunkey River to screen his movements from the Confederates. He ordered (on May 22) that his supply depots at Belle Plain, Aquia Landing, and Fredericksburg be moved to a new base at Port Royal, Virginia, on the Rappahannock River. (Six days later the supply base was moved again, from Port Royal to White House on the Pamunkey.) He ordered Brig. Gen. James H. Wilson's cavalry division to cross the North Anna and move west, attempting to deceive Lee into thinking that the Union army intended to envelop the Confederate left flank. The cavalry destroyed more sections of the Virginia Central Railroad during this movement, but had no significant enemy contact. After dark on May 26, Wright and Warren disengaged and stealthily crossed over the North Anna. They marched east on May 27 toward the crossings over the Pamunkey River at Hanovertown, while Burnside and Hancock remained in place to guard the fords on the North Anna. The Union cavalry under Maj. Gen. Philip Sheridan had returned by this time to screen the advance. The army's eventual goal was the important crossroads of Cold Harbor, southeast. Grant's optimism and his reluctance to assault strong defensive lines would be severely tested in the upcoming Battle of Cold Harbor. In the meantime, North Anna had proved to be a relatively minor affair when compared to other Civil War battles. Union casualties for the four days were 2,623. Confederate casualties were not recorded, but based on the bloody fighting between A.P. Hill and Warren, it is probable they suffered between 1,500 and 2,500 casualties. Battlefield preservation The North Anna Battlefield Park, opened in 1996 and maintained by Hanover County, Virginia, preserves a small section (75 acres) of the battlefield. Walking trails are available to inspect portions of the left side of the "inverted V" Confederate line up to Ox Ford. In 2011, the Board of Supervisors approved a conditional use permit allowing expansion of the rock quarry (now operated by Martin Marietta Materials Inc. and American Aggregates Corporation). As part of the approval, the owner donated 90 acres to the County, including what is called the “killing fields” where the heaviest fighting took place. The overall park now consists of 165 acres. In 2014, the American Battlefield Trust, formerly known as The Civil War Trust, acquired and preserved a 654-acre farm at the Jericho Mills part of the North Anna battlefield. As of November