Gen. Mark A. Milley, chairman of the Joint Chiefs, must go. President Biden claims that the military advised him to close Bagram Air Base in Afghanistan and instead use Kabul’s airport to evacuate Americans. They were the ones who said the Afghan army would hold, that the pullout would go smoothly. If Biden is telling the truth, this disaster is on Milley’s watch. Or Biden is lying (the more likely scenario, based on what sources inside the administration are saying) and Milley failed to do his duty and push back against a commander-in-chief who is making deadly decisions. Either way,...