Final answer:
Virginia seceded from the Union in 1861 due to valuable resources, heritage, and the addition of General Robert E. Lee to the Confederate side.
Step-by-step explanation:
Virginia seceded from the Union on April 17, 1861, because of several reasons. Firstly, Virginia brought valuable resources to the Confederate war effort, including the Tredegar Iron Works, which was the only plant in the South capable of manufacturing heavy artillery. Secondly, Virginia's heritage as the home to three presidents brought greater prestige to the Confederacy. Lastly, Virginia's secession brought General Robert E. Lee to the Confederate side, who was considered one of the best military commanders of the time.