Originally from Corellia, this ex-Imperial commander proved invaluable to the Alliance. Unlike some of the other Imperial commanders, Madine treated his troops fairly. He brought home many victories and was placed in command of an elite commando unit. With this unit, Madine proved his worth and suffered few casualties among the ranks under his command. But most important of all, to him anyway, they commited no attrocities of war.
But his conscience would eventually drive him to the Rebellion. It was said that his last mission came directly from the Emperor. The mission was never completed, as Crix thought the orders so inhuman that it would be attrocious to carry them out.
When he contacted the Alliance, the Rebels thought he might have been a double agent, but with the recommendations of General Reiekan behind him. the High Command Advisory Circle accepted him. In the end he became chief military advisor to Mon Mothma, who knew all about Madine's Imperial background and knew he would be able to bring some new perspective to Rebel tactics. He did, and the ground tactics were revised and given a new look. These new innovations and concpets were instrumental during the Battle of Endor.
While Ackbar directed the battle in space, it was up to Madine to devise a plan to take out the shield generator on the forest moon of Endor. He knew he had a very good strike team, lead by Han, so he planned around them. In the end these plans worked, the shield generator was destroyed along with the second Death Star, and the Alliance was victorious.
He has never wanted to leave the job of devising new tactics for the New Republic's ground troops, and has been intrumental in many battles since Endor. He helped defeat Thrawn, and then he managed to find a way to destroy the World Devastators that threatened to take the galaxy apart planet by planet.
He fights for peace, and knows that one day, peace will come. It always does.