The Civil War was the most lethal conflict in American history, by a wide margin. But the conventional metric we use to measure a war’s impact – the number of human lives it took – does not fully convey the damage it caused. This was an environmental catastrophe of the first magnitude, with effects that endured long after the guns were silenced. It could be argued that they have never ended. 

All wars are environmental catastrophes. Armies destroy farms and livestock; they go through forests like termites; they foul waters; they spread disease; they bombard the countryside with heavy armaments and leave unexploded shells; they deploy chemical poisons that linger far longer than they do; they leave detritus and garbage behind. 

As this paper recently reported, it was old rusted-out chemical weapons from the 1980s that harmed American soldiers in Iraq – chemical weapons designed in the United States, and never properly disposed of. World War II’s poisons have been leaching into the earth’s waters and atmosphere for more than half a century. In Flanders, farmers still dig up unexploded shells from World War I.

Now, a rising school of historians has begun to go back further in time, to chronicle the environmental impact of the Civil War. It is a devastating catalog. The war may have begun haltingly, but it soon became total, and in certain instances, a war upon civilians and the countryside as well as upon the opposing forces. Gen. William T. Sherman famously explained that he wanted the people of the South to feel “the hard hand of war,” and he cut a wide swath on his march to the sea in November and December 1864. “We devoured the land,” he wrote in a letter to his wife. 

Gen. Philip H. Sheridan pursued a similar scorched-earth campaign in the Shenandoah Valley in September and October 1864, burning farms and factories and anything else that might be useful to the Confederates. Gen. Ulysses S. Grant told him to “eat out Virginia clear and clear as far as they go, so that crows flying over it for the balance of the season will have to carry their provender with them.” ...