Army of Virginia
By July 1862, Stahel was commander of the first brigade of Robert C. Schenck's first division Army of Virginia in the corps led by Franz Sigel in Maj. Gen. John Pope's Army of Virginia. At the Second Battle of Bull Run, Schenck was wounded and Stahel became acting commander of the division. (Adolphus Buschbeck succeeded to command of the brigade.) Stahel's brigade was one of two that covered Sigel's retreat when Pope's army was defeated.