The significant landmark that Union forces used as a defensive position was Cemetery Ridge.

This elevated landscape offered an advantageous viewpoint for Union troops during the Battle of Gettysburg. Situated along Cemetery Ridge, Union forces created a robust defensive line that enabled them to withstand Confederate attacks, especially during the crucial confrontations on July 2 and July 3. The ridge's natural defenses and strategic positioning played a crucial role in securing control of the battlefield, ultimately aiding in the Union's victory in this pivotal conflict.