General Mattis and Jeff Sessions are in similar positions in that their standing with the White House is/was somewhat obfuscated. Mattis and Sessions have served their purpose and now it is time to move on. General Mattis was in a position where he could voice his opinion but was bound by duty to follow orders. Apparently, Mattis had a problem with that. Mattis' disdain for the POTUS was revealed by the 50 copies left of his resignation. Thank you General for serving your country. Now get out of the way.