Tau V Space Marines Loss

Horrible loss, a game I want to forget I deployed to thinly and my opponent had an army of grav-cannon centurions which with night fight and him ceasing really hurt me. I had planned to use my railguns+fusion weapons to kill/wound a number of them off very quickly and try to finish them off with pulse shots. The centurions marched up the board and took out my hammerheads which was game over, I managed to kill 3 centurions and my opponent tabled me. I should have deployed much closer together and had lines of fire warriors screening my tanks from the on coming centurions. Doing this would have bought me time to re-deploy and shoot them up a bit more.