Liland,

the song is originally from France. It was sung by by the French going into action at the battle of Malplaquet in 1709, where they were beaten by the Duke of Marlborough.
(Singing a special song was often used as a mark of identification in the fog of powder, where uniforms and flags couldn't be seen well, or to show a certain presence. So at Langemarck in Flanders, where the German volunteers sang the National Anthem - not for jingoism, but to show the own artillery that they were shelling the wrong troops.)

Wilfried