Trump is a draft dodger whose family paid a doctor to get him out of the service with a bone spurs diagnosis. And he not only shits on General Mattis, who is a highly revered Marine who served in the Gulf War, Afghanistan, and the Iraq War and has military decorations that REQUIRE being in combat, including a Bronze Star with a Combat V, he takes it a step further and claims that he gave him the Mad Dog nickname, a nickname Mattis actually received from his fellow Marines over a decade ago. Marines defend their culture zealously. I can't see how he has any support left in the USMC after tonight.
Also, lest we forget, Trump also shit on Admiral McRaven. Trump might as well cover all his bases and throw General Clarke and General Goldfein under the bus. Hell, talk shit about Audie Murphy, too. That'll show the military who's boss...