This might be the song that gnomad referred to back on 11 Nov 01 – 10:10 am—but note the difference in verb tense: "When we wind up..." rather than "When we've wound up...". Also, see the footnotes.

From the sheet music at The Levy Collection:


WHEN WE WIND UP THE WATCH ON THE RHINE
Words by Gordon V. Thompson, music by Gordon V. Thompson and William Davis.
New York: Leo Feist, Inc., 1917.

1. Now we must part,
Heart of my heart.
I can hear the bugle sounding with a call so clear.
Till I return,
My heart will yearn
For the girl I leave behind me in the homeland dear

CHORUS: When we wind up the watch on the Rhine,
And we grind up the Kaiser's last line,
When the war is done and the victory won,
I'll come back to the girl that I call mine.
When we wind up the watch on the Rhine,
We will bind up two hearts that entwine.
Wedding bells will be ringing.
"Home Sweet Home" we'll be singing,
When we wind up the watch on the Rhine.

2. Just one short line,
Sweetheart of mine:
I am battling for my country far from home tonight.
Though foes assail,
Right must prevail,
So keep knitting still and smiling till we win our fight.


[The title is a punning reference to a German patriotic anthem Die Wacht am Rhine (tr. The Watch on the Rhine).]

The National Library of Australia has sheet music described thus (but it is not viewable online):

WHEN WE'VE WOUND UP THE WATCH ON THE RHINE
Words by F. W. Mark, music by H. E. Darewski
Melbourne & London: Allan & Co. Pty. Ltd.; Francis, Day & Hunter ©1914.
"Sung by Jack Cannot in the Tivoli Follies. Also by Sydney James and the Royal Strollers"

The British Library has sheet music described thus (but it is not viewable online):

WHEN WE'VE WOUND UP THE WATCH ON THE RHINE
by J. Urquhart Ireland
Winnipeg & Toronto: Whaley, Royce & Co., ©1916.