The correct option is "A direct attack on open ground causes large numbers of casualties."
The Battle of Gettysburg was a battle of the American Civil War, fought between July 1 and 3, 1863 around the town of Gettysburg, Pennsylvania, as part of the Gettysburg campaign. It was the battle with more casualties in the United States, which is considered the turning point of the American Civil War (1861-1865) along with the site of Vicksburg; and that, in addition, marked the beginning of the Union offensive, it was a great victory for the Federal Army (Army of the Union) and a disastrous event for the Confederation.