I was at work a couple of weeks ago organizing a new collection and found an article that stated Ulysses S. Grant was a slave owner. Of course, this peaked my interest as something you don't often hear about. The article claimed that Grant had owned slaves longer than Lee did. So I decided to do some research.
Julia Dent Grant came from a slave-owning family and was an apologist for slavery throughout her life and the Civil War. The Grants owned slaves that came from Julia's father and Grant himself was responsible for supervising them. These slaves were not freed until 1865 when Missouri officially abolished slavery.
Grant actually owned one slave himself as well:
Grant himself owned a slave named William Jones, acquired from his father-in-law. At a time when he could have desperately used the money from the sale of Jones, Grant signed a document that gave him his freedom.
Grant freed this slave in 1859.
Robert E. Lee came from a slave-owning family, but upon his father-in-law's death, all those slaves were freed (this was 1862 before the Emancipation Proclamation). In a letter to President Pierce, Lee wrote that "There are few, I believe, in this enlightened age, who will not acknowledge that slavery as an institution is a moral and political evil."
So what is comes down to is the Grant family owned slaves longer than the Lee as the slaves in question were from Julia's family, not Grant's personal slaves. That being said, of course, in that day and age, that meant Grant was in control of them. It is interesting to see that both of these men - the two opposing Civil War generals - were slave owners at one point or another in their lives.