. Lomax stopped at Auburn to wait for Stuart and dispatched scouts further east who soon discovered Brig. Gen. John Buford's cavalry at Warrenton Junction, guarding the Federal wagon train advancing east by the O&A railroad. No scouts were dispatched to the south however, and the presence of the Union II and III Corps, which had become separated from the main body of the Union army due to confusion during the frequent repositioning of the past few days, marching north toward Auburn.