In the series Chronicles of Narnia what does Aslan do to save Edmund?

In the Chronicles of Narnia series, Aslan does not save Edmund. Edmund betrays his siblings and joins the White Witch, but he is eventually captured and put on trial by Aslan. Aslan offers to spare Edmund's life if the White Witch will sacrifice her own life in his stead. The White Witch agrees, and Aslan kills her with his claws. This act of self-sacrifice saves Edmund and allows him to return to Narnia with his siblings.