Read Breitbart and the other far right and Alt Right sites. You can see why Bannon had to go-- he opposed more troops and the far right and Alt Right gang strongly oppose continuing the war in Afghanistan as they did the missiles fired at Syria. That included Trump In the campaign. BAnnon and his bizzaro right wing followers are today smearing  McMasters who helped draw up the plan. Saying he is a drunk and believes in "kissing the Koran"-- literally-- to aplogize for thing like civilian casualties or troops insulting Muslims. Bannon and followers will keep pushing to get McMaster out.