Paul Morphy is widely considered the greatest chess player of his era, and is often referred to as an unofficial World Champion.

If you are like me you enjoy playing chess but hate losing more
often than you win. For me at least, winning often seemed more
of an accident than skill. Well, having many hours of trial and
error, studying moves my opponents made, looking at what I was
doing, etc. I came up with a few basic ideas on [...]