An intriguing little snippet:
Roman Empire ran on camel power
Now it probably didn't, but it's _just_ possible that camels were more significant than we thought, it's just that we haven't discovered an image of camel using soldiers from a grave marker or had a written account.
Now if they were really common you'd think we'd have reasonable material evidence and you'd probably be right. But we do know that there were all sorts soldiers from all over the empire stationed in wierd places - just look at the roster for the regiments manning Hadrian's wall.
So it's possible that there were camel using troops in Belgium, just that there were only a few detachments.
And the camels were eaten, failed to thrive, and passed from memory ...