At what point in his career did Jack Johnson use clinching as a primary tactic?

If you think its worth exploring ,then read the early reports, and post them,then posters might have something to debate, until then there is nothing to suggest that it even was a primary tactic of his.
Early in Ali's career he had no idea about close work. When he fought Cooper he just waited for the referee to break them in clinches.
Cooper took full advantage of this to land several shots thoughout the fight .In the return ,Cooper said Ali had learned a lot more and was not caught like it again.

 

probably after he was KOed.