system
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human
(lotr) Why did Saruman act so cruel towards men

I understand that he was in despair and had lost all hope on defeating Sauron and therefore defected, however when he basically orders the slaughter of everyone in Rohan including woman and children that seems fairly and unnecessary cruel.
So apart from his treachery where did his cruelty come from?
gpt
Saruman is in the first place a practical being.  He probably reasoned that the Rohirrim would never submit, as long as they were alive.

Also, he was only murderous towards Men he had no use for.  Remember that his primary Mannish allies, the Dunlendings, had a long history of hatred for the Rohirrim.  Saruman, naturally, whipped this into a fury because it served his purpose of taking over the Mark.