How to enable salesforce track field history?
Salesforce starts tracking field history from the date and time that you enable it on a field. Changes made before this date and time aren’t included and didn’t create an entry in the History related list. '
I just enabled history tracking on the 'Close Date' field on Opportunity. Can we retrieve field history prior to enabling via API or any other way?
No, it's not possible. There's just no data recorded in the first place prior to enabling salesforce track field history on the field.