Lee vigorously opposed slavery and as early as 1856 made this statement: "There are few, I believe, in this enlightened age, who will not acknowledge that slavery as an institution is a moral and political evil." 

Lee also knew that the use of slaves was coming to an end. Cyrus McCormick’s 1831 invention of the mule-drawn mechanical reaper sounded the death knell for the use of slave labor. Before the War began, 250,000 slaves had already been freed. 

All that inventive genius was sidetracked into the war effort in 1861. Instead of focusing on machinery that could have prompted the end of slavery, the focus was now on building war machines like iron clads, submarines, sea mines, hand grenades etc., all products of Southern inventiveness.