The battle of Gettysburg lasted three days from July 1 to July 3, 1863. There were more than 50,000 casualties in those three days. George Meade's Army of the Potomac defeated Robert E. Lee and the Army of Northern Virginia.
One thing that surprised me about actually visiting Gettysburg was just how many Confederate memorials there were there, and how they were often bigger than the Union ones. Like, this was supposed to be the site of a *UNION* victory! But you could barely tell that by the monumentation there...