Movie was made in the 60's 0r 70's. Took place on an Island. I believe it was Americans and Japaneze. Both sides sent one guy to the Island the last one standing captured the Island. In the end they killed each other and battle began all over. What was the movie?

Could be, "Hell In The Pacific".

Sounds like The Challenge (http://www.imdb.com/title/tt0065534/) from 1970.