My uncle did not like my father but yet he has his ashes. My brothers and myself would like his ashes, we believe the ashes should be in our possession. Who do I have to contact to fight for my father's ashes?

Assuming that your father left no directive in his will regarding disposition of the ashes, the executor of your father's estate makes the decision.

My advice is rather than fight over who keeps them, think instead about disposing of them someplace appropriate - you can make a family ceremony which just might help smooth over some of the animosity that I sense here. Also, there's no reason that the ashes can't be divided up - have you suggested that to your uncle, or to the executor?