Merci Loïc ! Au Maroc en 1940 donc. Possibly to maintain security along a major railroad then.
Looking further, I found that the French also had two armored trains deployed in Indochina in WW2, one in Tonkin and one in Cambodia. The latter participated in the war against Thailand patrolling the railroad between Phnom Penh and Poipet but never opened fire in anger.
The same post also mentioned a Spanish Republican armored train that ended up in France at the end of the Spanish civil War.
Source: http://deuxiemeguerremondia.forumactif. ... oie-ferree
In addition, the French Army used a first then a second armored in Indochina in 1946-1948
Source: http://fr.wikipedia.org/wiki/Chemin_de_ ... re_(France