True. I think that I heard on a Civil War documentary that Lee freed his slaves prior to the war and that Grant kept his wife’s slaves until the war ended.
You would be wrong on both counts. Lee freed the slaves left by his father-in-law's estate in December 1862, almost 2 years after the secession. The slaves Grant's wife had use of were owned by her father. All Dent family slaves were freed early in 1863. Regardless, Missouri outlawed slavery in January 1865 so there was no way Grant or his wife or anyone else in the state could have owned a slave.