For three years the Great Landsraad House Atreides was growing weary of the feuding on Arrakis. Finally after a succession of horrible defeats at the hands of their enemies the Atreides have sounded the retreat and are now departing the warring planet of Arrakis for their homes on Caladan. The Atreides diplomats called an emergency session of the Landsraad Council and began negotiating with their enemies, in an effort for a final peace for the honorable house. The Atreides Duke approved many concessions and compromises, and spent fully a third of his house's outside resources buying peace for his people. But the Duke has not abandoned his allies on Arrakis yet.
The Fremen have gained much of their planet from the Atreides, for as the great house retreated their forces, the territories they formerly controlled were left to the desert warriors. The Fremen are finally given the chance to fight once again for their freedom and inadvertently for the freedom of the Empire. For should the Fremen be able to liberate their world, they would not see it taken again by any force. Thus the spice would be gone from the shelves of Imperial merchants and traders, the Empire would face the most horrible plague in it's history. The spice addiction would cause withdrawals within the bodies of it's sufferers of such potency that death would almost inevitably fall.
Though the Fremen now control a huge section of Arrakis, they did not at first have the equipment and man power to hold and manage it. The Fremen begged the retreating House Atreides to make good on their mutual water debts and treaties, and requested equipment and soldiers. The Atreides saw an opportunity to strike their enemies one last time and they took it. The Atreides frigates departed Arrakis, but in their stead would remain a well equipped militia force. These forces represented the most advanced force of fighters in the universe, a force to rival the Emperor's Sardaukar and even the Fremen Fedaykin Warriors. With the might of the Atreides equipment combined with the battle hardened Fremen, surely only decisive victory would mark this war's end.
-Timenn & Inoculator9