I just had a flash of a Zouave (French colonial soldier). He was lighter-skinned than the others, looked to be a fair-skinned Arab or Berber, but his mustache was just like the ones worn by the home grown Poilus. I think he was an officer whose hair was the same golden tone as his skin and whose nose was aquiline, and it seems like it was common for the low-ranking native officers among the colonial regiments of France and britain both to be fair-skinned and with features that fit the European image of nobility.
I will owe some apologies if this turns out to be false.
By the way, the bravery of the colonial troops is sometimes dismissed because they fled from the gas, but at that point their position was not tenable because the gas would have killed too many of them to hold the line. Anyone who understands strategy would have approved of a retreat in this case. Their retreat could have been more orderly, but the gas was moving quickly and was causing real problems that had to be dealt with then and there. If there was anything lacking it wasn’t bravery, but planning for the eventuality of an unstoppable offensive action and that was not unusual among commanders of the day. If the French were attempting to follow the British strategy of no retreat, ever, then that’s not the fault of the colonial troops faced with losing the line completely or getting away fast.