Actually France supporting us was more analogous to us supporting the Mujahadeen. Their enemy was our enemy.
Point is, they weren't involved in that particular war until they came to our aid. Had we gone down, they would have soon joined us at the hands of the British. Everyone else, it seems, wants us to send in our troops whenever they get in a jam or wish to garner more of our taxpayer's money for acting friendly (ala' UN).