We go to space anon. Rome ruled a vast empire but not in the Western Hemisphere. It's a matter of distance. The British Empire was supreme in power but only where they could reach in any numbers. The Royal Navy could not reach the mountains. They had needed our timber for their ships since we had the oak. The soldiers were actually few, that's why the Hessian mercenaries were needed. We spread out among the Solar system and make it so oppressors cannot concentrate enough force to overcome the locals. Say Earth runs the show and Neptune rebels, forces deployed to regain control but meanwhile Mars goes rouge, builds a fleet. Earth cannot keep overwhelming forces everywhere all the time so when scurrying with the Neptune/Mars whack-a-mole runs into rebel Saturn and a fleet from Jupiter. Typical military planning is 12 occupiers needed to counter 1 partisan. Numbers go up high enough and occupation is just not tenable for long when it takes weeks to months to get reinforcements anywhere.