The Subjugation of the Harry Potter Dimension was the conquest and subjugation of the Harry Potter dimension by the Galactic Empire in 1 BBY. The subjugation was lead by Darth Vader.
In 18 BBY, the Galactic Empire, the dominant Universal government, had attempted to destroy a Jedi enclave at Hogwarts Academy in the independent Harry Potter dimension. This would have also destroyed the Hogwarts magicians, one of the ruling groups of that dimension. However, this plot had been foiled by Hogwarts students, in cooperation with the leaders of the Jedi enclave. The Jedi managed to escape. However, the dimension remained outside of Imperial control, and would be independent for a further 17 years. During that time, the Empire, whilst continuing it's oppressive rule over most of the rest of the Universe, also developed more sophisticated projects at the Maw Installation, to allow a successful destruction of the magicians and the conquest of the dimension. This had resulted in the construction of the magically-resistant Star Destroyers, as well the development of a weapon, the Destroyer, which could quickly eliminate the magicians. Finally, in 1 BBY, the Empire launched the invasion, which was commanded by Darth Vader, the Supreme Military Commander and the Emperor's Sith apprentice.
A Imperial fleet of 30 Star Destroyers, 10 of which were magically-resistant, appeared in orbit over the Harry Potter dimension. Vader immediately demanded the dimension's surrender. The Hogwarts magicians, however, refused, and launched a trick at the Imperial fleet. 2 of the non-magically resistant Star Destroyers were quickly immobilized, but the resistant ones promptly destroyed numerous Harry Potter military garrisons and Hogwarts outposts, considerably weakening the strength of the defenders. The magicians again attempted another trick, which brought down another Star Destroyer, but by then, it was too late. Vader's flagship, the Executor, which itself had been constructed as magically resistant, unleashed the firepower of the Destroyer superweapon against Hogwarts Academy. The Academy was promptly destroyed, and all but three of the Hogwarts magicians (who were Harry Potter, Hermione Granger, and Ronald Weasley, the commanders of the defense force) were killed.
With the extermination of the Hogwarts magicians, Vader ordered the landing of stormtroopers in the dimension. Millions of them, as well thousands of AT-AT Walkers, deployed to the dimension. The Harry Potter defense forces, heavily demoralized by the loss of their magical protectors and primary commanders, were beaten back on most fronts, despite the rallying of Potter, Granger, and Weasley. However, Imperial forces suffered moderate losses, mainly due to the efforts of those same three Hogwarts magician-survivors.
Despite the efforts of the Hogwarts survivors, the Imperial forces eventually gained victory. Star Destroyers in orbit destroyed most of the surviving military bases, outposts, and garrisons, thus insuring the final defeat of the defense force. The Harry Potter Civilian Council were forced to surrender, thus bringing their dimension under formal Imperial control.
In the wake of the dimensional government's surrender, the Empire promptly instigated it's occupation. More then 400,000 Harry Potter prisoners of war were moved to Imperial containment camps set up near the smoldering ruins of Hogwarts Academy. However, Harry Potter, Hermione Granger, and Ronald Weasley all escaped into hiding, taking some of the military forces who refused to surrender with them. They quickly established a resistance cell which has hampered the Empire's control of the dimension to the present day.