Just for the record, when an imperial state needs to use its regular armed forces to keep the peace in a colony, its colonial adventure is in real trouble. That is not how colonialism works. The idea is for the army to conquer and as quickly as possible turn the colony over to a lackey regime, which will maintain domestic peace with its police force on behalf of the imperial ruler. Imperial troops mostly leave the colony altogether! And the rest (this is a secret), return to their barracks and stay out of sight (that's the secret part, as in 'they secrete themselves away out of sight). An alternative approach is for the imperial power to recruit locals into its army and post them, with imperial officers, to maintain local control. Still another approach is to put a minority in control, since, being the minority, it will be totally dependent on the imperial power to maintain its authority.
Perhaps the above was unclear. Let me make the case in different words: the movement of imperial forces off the streets of the colony has nothing to do with returning sovereignty. On the contrary. It is precisely about institutionalizing the colonial adventure.
The last thing a great global imperial power can afford is to have its army mucking around fighting battles against its colonial subjects. Battles can be fought - but by mercenaries, not by the imperial forces. The imperial forces will inevitably be needed for new wars (e.g., against still independent countries on the borders of the colony).
The withdrawal of imperial troops from conquered cities to distant rural outposts of a colony constitutes a critical victory for the empire and a defeat for the colonial people, who will lose their target without gaining their freedom.
Of course, the above is just the theoretical musings of a political scientist. You figure out whether or not it bears any relationship whatsoever to any real-world events!