The decisive battle of the American Civil War is often considered to be the Battle of Gettysburg, which took place in Pennsylvania rather than Virginia. However, if you are specifically looking for a significant battle fought in Virginia, you might be referring to the Battle of Appomattox Court House, where General Robert E. Lee surrendered to General Ulysses S. Grant on April 9, 1865, effectively leading to the end of the war.
If you meant another battle or a different context, please provide more details!