This is the part I really wanted to get to… because it's so good!
Follow Deathwings defeat, the goblin engineers manged to repair the Twilight's transmitter and sent a signal to the Republic. The Chancellor and Jedi Counsel learned about the planet and its inhabitants (but the events of the Cataclystem were kept a secret). After the Republic found out about Azeroth, the Separatists and the rest of the galaxy found out too.
Both sides wanted this new planet on their side. It was at this time Garrosh and the other Horde leaders found out the truth about the two factions. The Republic was anything but a republic, all senate cared about was it's wealth and power, and not much else. And the Confederacy of Independent System claimed to want freedom, but enslaved other people. As such Garrosh decided that the Horde would remain neutral, even calling both governments lyres and hypocrites. The Alliance was a different story.
I like the Horde better than the Alliance, so I have my own version of WOW.
King Varian wanted to destroy the Horde and all its citizen, and as for is "allies", he saw them as nothing more than tools. The advanced weapons of the Republic intrigued him. He offered to help with the war effort, he offered to build weapons, warmachines, etc., and in exchange they would give the Alliance advanced technology and a place in the Republic. They agreed.
Garrosh saw an opportunity to expand the Hordes territory to the stars. He manged to purchase enough weapons(blasters, tanks, rocket launchers, etc.) and starships to form the Hordes first armada, under the command of General Nazgrim. He sent out to conquer the unallied systems like Datootwine and Lothal.
The course of history has changed on Azeroth… forever. And no one knew what the future would hold.
The End
Let me know if you want me to write a sequel in the reviews?