Perhaps part of the answer can be found in the following, describing the movement of General Early's "Army of the Valley" into the Shenandoah Valley after the Battle of 2nd Cold Harbor.

"On June 15, 1864, the troops passed through Louisa in the morning and at Trevilians , took the road to Charlottesville. On their route, they passed the site of some recent cavalry engagements where a great many dead and swollen horses lay on the ground and numerous new graves attested to the severity of the contests. By the end of the following day, they were within five miles of Charlottesville and made camp near Shadwell at Keswick Depot." (Source: “Flank Attack” by James K. Swisher, America’s Civil War Magazine, September 1993, page 36)

The Confederate Cavalry had been harassing Hunter with limited success. Wasn't Sheridan in Washington in early June 1864, or with Grant?