Virginia became a prominent part of the Confederacy when it joined during the American Civil War. As a Southern slave-holding state, Virginia held the state convention to deal with the secession crisis, and voted against secession on April 4, 1861. Opinion shifted after April 15, when U.S. President Abraham Lincoln called for troops from all states still in the Union to put down the rebellion, following the capture of Fort Sumter. The Virginia convention voted to declare secession from the Union on April 17. A Unionist government was established in Wheeling and the new state of West Virginia was created by an act of Congress from 50 counties of western Virginia, making it the only state to lose territory as a consequence of the war.