Gandalf tells King ThÃ oden that they have to go to war against Saruman . Gandalf assures them that Merry and Pippin are safe , and they travel instead to rouse ThÃ oden , King of Rohan , from a stupor of despair inflicted by Saruman , and to aid the Rohirrim in a stand against Saruman 's armies . ThÃ oden fortifies himself at Helm 's Deep along with Aragorn , Legolas , and Gimli while Gandalf rides off to gather more soldiers .