[buwaya]

Not a bad idea on the face of it. Its been done before, and very well. The French conquered and subdued much of their empire with the Foreign Legion and local native troops.
European officered Senegalese (just an example) would put the fear of, well, something in the hearts of the Arabs. They certainly scared the Moroccans.

The real problem is direction. If whoever was picking up the tab put the job of both organizing the army and running the war in the hands of a Hubert Lyautey or John Glubb or even David Petraeus and let him get on with the job it would be done well. The real problem is that the real leadership will be in the mishmash of an international coalition with no direction.

[gusty]

Times have changed. In those days one joined the military with the expectation that they would spend years, even decades, away from the homeland. Armies in the late 19th Century were not all concerned about the soldiers family life. There was no yellow ribbons tied around trees. The British Army encouraged its men to go native. Native in that cohabiting with the local females was not frowned upon. A fresh officer would be sent to the Northwest Frontier, we call it Waziristan today, and he did not expect to return to England for years upon years. Thus he usually did not marry and start a family until his 40’s after his service was over, not during like we do it today.

Sometimes things went horribly wrong. One French force's commander went Kurtz, and launched a killing spree that would have horrified Reinhard Heydricht. The French had to send another column into the interior to destroy the rogue force, which they did with heavy casualties.