The graph to the left shows the total losses of Confederate forces throughout the war. On the x axis are various battles labeled chronologically. After Gettysburg there is a steep incline of casualties placing the Confederates losses at over 200,000. From there the amount of dead only rises. Also, the slope of the graph decreases after Lee resigns. This shows the South's loss of military ability after Gettysburg.
This image is from: http://www.atimes.com/atimes/Middle_East/EF12Ak01.html