The movement to end the slavery is calles abolitionism, This movement existed before and during the Civil War (April 1861 - May 1865) in the Unites States.
The answer:
States that attempted to end slavery during the war were:
Maryland (November 1864)
Missouri (January 1865)
Tennessee (January 1865)
West Virginia (February 1865)
District of Columbia (1862)
