Posted in the pre-1900 forum, but post-1900 PODs are acceptable as well.
Thinking back on how France turned Algeria into a settler colony, and how nasty that situation made it for all concerned when the inevitable eventually happened and the place became independent, I thought of a challenge: have a Western power (defined as Western European or American) claim Mesopotamia as a colony anytime between 1800 and 1950, and have Westerners come to said colony as permanent settlers until they amount to a plurality of the population.
All of these settlers may not necessarily be from the colonizing power, just as a fair percentage of settlers in Algeria came from Spain and Italy rather than France itself. But their loyalty should definitely go to the colonizing power.