I cannot give a yes/no answer to you as to if your teacher in the 1960s was right to smack you over your dress. It all depends on where the school was and if such things were socially accepted.
The four crunch questions are
Do your parents know? If they did and said nothing then it was acceptable Did others get it like this? If parents knew this smacking was going on then it is unlikely that any real offence was being committed.
Did you deserve it? If no you may have a case
Did it feel he was really smacking your bottom or fondling it?
If the latter you may have a case.