""I intend to fight it out along this line if it takes all summer,"" Union commander Ulysses S. Grant wrote to Washington after he'd opened his Overland Campaign in the spring of 1864.His resolve entirely changed the face of warfare.Promoted to command of all the Federal armies, the new lieutenant general chose to ride shotgun with the Army of the Potomac as it once again threw itself against the wily, audacious Robert E. Lee and his Army of Northern Virginia. But Grant did something no one else had done before: he threw his army at Lee over and over again.At Spotsylvania Court House, the seco