Versions of it are found all over France and Canada, so I'd assume that it began in France.  In France it's more usually called Le Canard Blanc or Derrière Chez Nous, and is a good bit older than WWI.  There are a lot of references to V'la le Bon Vent on the Web, but they all seem to relate to the best-known Canadian version, and all the musical examples are copies of Barry Taylor's midi arrangement, which may be found at  Barry Taylor's Great Canadian Tunebook  It might be possible to extract chords from that, using a programme like Midinotate, if you really can't work out your own.

Malcolm