On this day, the Army of the Potomac embarks on the biggest campaign of the Civil War and crosses the Rapidan River in Virginia, precipitating an epic showdown that eventually decides the war. In March 1864, Ulysses S. Grant became commander of all the Union forces and devised a plan to destroy the two major remaining Confederate armies: Joseph Johnston's Army of the Tennessee, which was guarding the approaches to Atlanta, and Robert E. Lee's Army of Northern Virginia. Grant sent William T. Sherman to take on Johnston, and then rode along with the Army of the Potomac, which was still under the command of George Meade, to confront Lee.
On May 4, the Army of the Potomac moved out of its winter encampments and crossed the Rapidan River to the tangled woods of the Wilderness forest. Grant had with him four corps and over 100,000 men. The plan was to move the Federal troops quickly around Lee's left flank and advance beyond the Wilderness before engaging the Confederates. But logistics slowed the move, and the long wagon train supplying the Union troops had to stop in the Wilderness.
Although there was no combat on this day, the stage was set for the epic duel between Grant and Lee. In the dense environs of the Wilderness, the superior numbers of the Union army were minimized. Lee attacked the following day—the first salvo in the biggest campaign of the war. The fighting lasted into June as the two armies waltzed to the east of Richmond, Virginia, ending in Petersburg, where they settled into trenches and faced off for nearly nine months.