Petersburg National Battlefield - http://www.nps.gov/pete/

Petersburg, Virginia, became the setting for the longest siege in American history when General Ulysses S. Grant failed to capture Richmond in the spring of 1864. Grant settled in to subdue the Confederacy by surrounding Petersburg and cutting off General Robert E. Lee's supply lines into Petersburg and Richmond. On April 2, 1865, nine-and-one-half months after the siege began, Lee evacuated Petersburg.