During the American Civil War the Rapidan River served as a portion of the front line between the Confederacy and the Union. The Old Plank Road connected Fredericksburg with Culpeper and crossed the Rapidan River at a location referred to as Germanna Ford. This ford was used extensively by the Union leading up to the battles of Chancellorsville, Mine Run, the Wilderness, and Spotsylvania Court House. The Battle of the Wilderness occurred from May 5 to May 7, 1864 in portions of current-day Locust Grove. Union Army Commander Ulysses S. Grant's headquarters were located 5 miles southeast of Germanna Ford on a hill near the modern-day intersections of Route 3 and Route 20.