The Military uses of the Palantiri.

[TheGreatElvenWarrior]

Originally Posted by Inziladun

I think the primary reason Sauron was blindsided by the Rohirrim was Aragorn. He had revealed himself by using the Orthanc-stone before leaving the Hornburg. That caused Sauron to ignore everything else and focus on Minas Tirith.

But as you said, that was before he left Rohan. Wouldn't Sauron know where the palanir was being used? If he wanted the heir of the Throne of Gondor to perish, then wouldn't he attack Aragorn first?