The military's top enlisted adviser -- a senior adviser to the Joint Chiefs chairman -- will be stepping down in the months to come, Pentagon officials told Military.com on Monday. Marine Corps Sgt. Maj. Troy Black will depart the post and retire from military service after the newly confirmed Joint Chiefs chairman, Air Force Gen. Dan Caine, chose not to renew Black's posting for another two-year stretch, one official said. However, that defense official stressed that, while Black would not be