Elevation was an important part in battle strategy. You always wanted to capture the higher ground. You would have a complete overlook of the battlefield and you could attack the enemy from above. This is exactly what Lee had in mind. Unfortunately for him, the Union had already taken position on higher ground so the Confederacy would have to march uphill to reach their goal, and that wasn't an easy task. Cemetery Hill, the highest part of Cemetery Ridge, is 503 feet (153 m) above sea level. Also, there is a shallow valley between the two ridges, making the march uphill seem even longer. Hood's march to Little Round Top was also uphill. The peak rises up to 650 feet (198 m) above sea level.
The terrain of the battlefield was also a huge factor in the Union's victory. Devil's Den, although not very high, was covered in boulders, making it hard for the the troops to march up in an orderly fashion. It was the same way at Little Round Top. Lieutenant Colonel King Bryan of the 5th Texas observed that, "The huge rocks forming defiles through which not more than 3 or 4 men could pass abreast, thus breaking up our alignment and rendering its reformation impossible."