Petersburg, Virginia, was the longest siege in American history and the the final act in the Civil War. When General Ulysses S. Grant failed to capture the Confederate capital, Richmond, during the spring of 1864, he decided to besiege nearby Petersburg instead, thereby cutting the Confederates' supply lines into Richmond.Nearly 160,000 troops endured almost ten months of brutal trench warfare and the inherent deprivations of winter sieges, but by March 1865, it was clear that Grant's forces would be able either to outflank the Confederate defenses or break their lines. On April 2 1865, nine and a half months after the siege began, Grant ordered an all-out assault and Lee's right flank finally crumbled. The Confederates surrendered at Appomattox Court House a week later.