What conclusion did Stanley Milgram reach on his obedience study that he conducted?

What Stanley Milgram concluded based on his famous study
of obedience is that people will do whatever they are told as long as they believe that
whoever is telling them what to do has the right to order them.  They will obey orders
from what they think is legitimate authority even if they are ordered to do terrible
things.

Milgram reached this conclusion because of how many
of his test subjects were willing to continue to press the button even when they thought
that, by doing so, they were hurting another person.  The study found that 65% of the
subjects were willing to continue to "shock" the person at the highest possible level. 
The subjects did this even though they sometimes felt that it was
wrong.

Because of this, Milgram concluded that people in
general (or at least members of his test group) are all too likely to follow immoral
orders as long as they think the people ordering them are legitimate authority
figures.