Harvard history phd student here - we admitted 7 people and have received approval to go immediately to the waitlist if any of them reject. So for those on the waitlist, there is a good chance we'll pluck a few from there. Our cohort this year will for certain be 7 people though which includes CMES. I think this year we received 400-500 applications.
If you are deciding on Harvard and other places, let me add that our funding package in the years to come will likely rise because of our union bargaining. Our 5 yr TT placement rate is around 80% with a lot of folks doing the JD/PhD and getting a job at a law firm afterwards. And we have guaranteed summer funding on top of our 12 month stipends. DM for more info.