Syd Hersh broke the story (we had actual reporters in those days), and won a real Pullitzer Prize (we don’t really have those anymore).
Calley (the fall guy) was initially sentenced to life in prison, but ultimately served almost no jail time.
Calley was only made an officer bc the Army was desperate for manpower. They relaxed intelligence testing standards, for which they have special legal dispensation from Congress. There are important reasons to protect meritocracy in all institutions.