The above coords will find you at a historical spot. Take time to do a little learning about the history that took place on these grounds.
Then when you're ready to calculate the second set of coordinates read the namesake marker and find the following;
The second number on the marker = A
The fourth number on the marker = B
"...the first of (how many? = C) desperate attacks..."
"...actual battle fought along a (how far? = D) mile front..."
C plus D = E
Find N33 48.CBE / W084 24.ACB
Follow your GPSr across the field of battle and find the final set of coords when you are directly under the supply route.
Follow the path to the final cache which is past a large tree growing atop a strategic position. Look about 50 feet further down the path for an easier access point to the cache. "Easier" is only on a relative basis as this cache earns its terrain rating in the last 150 feet to the cache.
Arriving at the final destination look for an ammobox stashed in a dark hole under a rock overhang.
Enjoy the hike and the challenge of geocaching - while also remembering the nearly 7000 Americans who died in bitter fighting here on this hot July day.