RWBY: TGW! AU: Mantle Missile unit

At the outbreak of the Great War, 81 years before the fall of Beacon to Cinder Fall, the Kingdom of Mantle was the most technologically advanced of the Four Major Kingdoms, in machinery, manufacturing, Dust manipulation...and weaponry. With their alliance with the Kingdom of Mistral, it was inevitable that they would lend their extensive firepower to the war against Vale, and their technological prowess saw rapid advances for the "Northern Alliance" early in the war. 

However, Vale was not without its technicians and engineers, and, partially aided by defectors from the aggressor kingdoms, began to hit back with weaponry of their own on par with that of their adversary. While some of it was shamelessly copied from Mantle gear, others were truly innovative, giving even Mantle scientists pause. Indeed, the success of Vale's Operation Nordwind three years into the war even put the kingdom on the back foot, especially when combined with Vale's surprise air strike on Mistral itself shortly after. 

King Maxim I of Mantle, outraged by these slights, lifted the restrictions he had placed on Mantle's involvement in the war: He had hoped the Emperor of Mistral could carry the bulk of the fighting, with his nation adding material and advisory support. Now, he committed the full force of his army, and Operation Gericht smashed open Vale's defensive lines and nearly drove to the gates of the capitol city itself. 

Lent to this offensive was Mantle's latest technological development: Intermediate range missiles that could be launched from well within the safety of the Alliance lines and strike targets anywhere in Vale. the Rockets, moving too fast to intercept, added to the rain of destruction the round-the-clock air raids were inflicting on the Kingdom. When Vacuo joined the war on the side of Vale, it too felt the sting of the rockets, with promises of even larger weapons to come. 

of course, the War ended with the climactic battle of Vacuo, but the potential of the Rockets would not fade as easily as the war had...

[=]

So, I've decided that, as the "Mother Maiden" Contest will keep me from posting "new" plot, i'm going to dabble in some AU Background. "The Great War!" AU will focus on the Great War itself, 80 years before the main series of RWBY.