Phillips concluded that plantation slavery was not very profitable, had about reached its geographical limits in 1860, and would probably have faded away without the American Civil War, which he considered needless conflict. His work on the subject is often overshadowed, however, by his praise of the entrepreneurship of plantation owners and denial of their brutality. Like most men of his time, Phillips believed that they provided adequate food, clothing, housing, medical care and training in modern technology—that they formed a "school" which helped "civilize" the slaves. He admitted the failure was that no one graduated from this school.