“Can the French foreign legion be deployed in times of crisis on French soil? Does any freeper know?”
The wiki doesnt specifically note such a restriction. But the history records no deployment within France. Perhaps France gas something similar to Posse Comitatus Act.
https://en.m.wikipedia.org/wiki/French_Foreign_Legion
Wiki does mention the Franco-Prussian War. I also believe the Legion was utilized in the suppression of the Paris Commune at the close of that war.