What was the impact of the Civil War on the environment?

The Civil War (1861–1865) is known as the bloodiest war in American history. It is also remembered for the Gettysburg Address and the end of slavery. It is less well-known for the enormous damage it inflicted on the environment.
Forests were cut down or burned by the fighting. Trees were cut down to impede an advancing enemy; limber was also needed for firewood or for use in military camps. Perhaps as many as two million trees were destroyed.
In 1864, General William T. Sherman's "March to the Sea" inflicted severe damage to Georgia's environment; everything in his army's path was either consumed or destroyed. Sherman thought his calamitous policies would help end the war, and he did not consider their impact on the environment.
Another destructive path was torn through the Shenandoah Valley in 1864. General Philip Sheridan proudly reported the damage to Grant after his campaign:

435,802 bushels of wheat, 77,176 bushels of corn, 20,397 tons of hay, 10,918 beef cattle, 12,000 sheep, and 15,000 hogs.

The monstrous damage suffered by the environment was largely due to the fact that the Civil War was a "total war"—especially by 1864. In addition, military and political factors always had more weight than environmental considerations.
http://fighting-the-earth.leadr.msu.edu/