The mademoiselle "hasn't been kissed [or other appropriate verb] for forty years." The soldiers complain about her or cajole her to do their laundry; they complain about their superiors (and their relations with the lady?) and grouse about army life
Both plot and tune of this song show a relationship with "Snapoo" (indeed, they sometimes mix, and Roud lumps them); it is reasonable to ask which came first and which influenced the other. As both appear at about the same time, however, it is effectively impossible to settle the matter.
Fuld has extensive notes about the origin of this song, with some interesting folkloric twists; the legends, while possible, are not convincing. - RBW