The death of Anakin's mother, Shmi Skywalker, conducted him to his first steps on the path to the Dark Side of the Force. In an act of anger and vengeance, Anakin slew everyone in the Tusken camp.
This event is a milestone in Anakin's fall, and we know Anakin is a crucial part of Darth Sidious's Grand Plan. So, is Shmi's abduction, torturing and death part of the plan? Did Sidious order, suggest, or cause those event in any way? Or, to the contrary, did he not even foresee them?