Who was the scapegoat for all the bad things happening in the farm?

Napoleon, aided by Squealer, uses Snowball as a scapegoat, which means that when something goes wrong, he blames Snowball.

Explanation:

Snowball is used as a scapegoat because he is wrongly blamed for everything that goes wrong or might go wrong on the farm. Napoleon scapegoats Snowball here because he knows that it is to his advantage to give the other animals a scapegoat to blame their problems on. Napoleon does not like Snowball's ideas and so has him chased off the farm by his guard dogs. We do not see Snowball after this incident. He is used by Napoleon as a scapegoat - anything that goes wrong on the farm is blamed on him.