I was wondering if anybody had any really cool histories/backgrounds for their armies and such. I always liked the idea that I could totally direct the course of my armies fate. Heres a fairly recent origin story for my IG army. (Igrone the corny ending).

Haliria has always been a desolate planet. One huge contingent surrounded by an endless glittering sea, the contingent is mostly desert with a huge mountain range on the west side of the landmass. There are two capital reasons that Halira was ever colonized. First, the entire ocean is drinkable, no salt water or impurities to clout its glory. Secondly, the mountains of Halira are chalk full of minerals, alloys and metals unknown to any other planet in Imperial space. Perhaps this is why the Nids’ came, perhaps they could not resist the planets flourishing populace but we do know that they came from nowhere. The desert cities fell first as the Planetary Defense Forces retreated in droves.
Just as the Tyranid horde reached the edge of the Mountains of Light an Imperial force led by Colonel Firnir, the commander of the Halirian 1st countered the alien offensive at Black Gun Pass. Firnir held the alien host for nearly two weeks before his full plan was implemented. Just as it seemed that the xeno’s would break the Imperial line a huge rumbling erupted from the back of the Tyranids lines. Firnir had only been holding the pass so that the 27th and 43rd Halirian Armored divisions could break the aliens backs with a well-timed attack. However just as the xeno’s were about to break, a suicide squad of Gargoyles attacked the 1st Regiments H.Q.
When the ruins were picked over and searched only two men were found alive. Colonel Firnir and Lieutenant Jason Zander were found and only a week later Firnir died of internal injuries while Zander lived on. Before Firnir died he acknowledged that Zander had led the defense of the H.Q. and personally defended the Colonel as the Nid’s got closer to the main command post. Firnir requested that Zander be promoted and that he be given the Colonels own blade as his last wishes.
Zander served for four years as a Captain in the 1st division and proved to be one of the most competent leaders of Halirian history. Zander has served five years as the leader of the 12th Guards division and in this space of time he has led the destruction of three Hive Fleets and nearly a dozen smaller splinter fleets. All of his men are veterans of wars with Orcs, rebels, Chaos and Dark Eldar, but their main prey are the Tyranids that pry the Eastern Fringe. However they are always known wherever they go as the Storm of Haliria.

So feel free to add your own armies story.