Who said this war is the father of all and king of all Some he sHow is as gods others as men Some he makes slaves and others free?

It appears in the prelude to "Life and Times of Michael K" by JM Coetzee. Given that it is not attributed, I would say (guess?) it is written by Coetzee himself.

No, it is a quote by Heraclitus; see also his philosophy as to the "unity of opposites"