After the fall of Khyber, people described the beauty of Safia Bint Hui, the new bride of a slain enemy soldier. The Prophet chose her for himself. On the way to Madina he camped and had intercourse with her. His companions did not know if she was a wife or a concubine. Later, a veil was drawn between her and the men-folk and they came to know that she was a wife. [Sahih Bukhari,Book of Sales and Book of Nikah 3:57 #78]. Elsewhere, the narrator of the wicked story states that Safia was initially given to Wahia Kulbi, but because of her beauty, the Prophet chose her for himself, and asked Wahia to pick another woman.
An important reminder: The Quran (47:4) ordains that prisoners of war are to be freed either for ransom or as an act of kindness. There is no third option. How could the Prophet (S) and his noble companions enslave human beings?