Arlington — The Arlington Historical Museum currently has on display an exhibit about a Union soldier from Massachusetts that was stationed in present-day Arlington County during the Civil War. The exhibit showcases items that belonged to John W. Bates of the 23rd Massachusetts Volunteers, who enlisted in August 1864. The items, which include a cannonball and bullets, were donated by Fairfax County resident M. Wesley Clark, the great-great-great grandson of Bates.