Lyrics below from The Lester S. Levy Collection of Sheet Music:

OVER THERE
George M. Cohan, 1917.

1. Johnny, get your gun, get your gun, get your gun.
Take it on the run, on the run, on the run.
Hear them calling you and me,
Every son of liberty.
Hurry right away, no delay, go today.
Make your daddy glad to have had such a lad.
Tell your sweetheart not to pine,
To be proud her boy's in line.

CHORUS: Over there, over there,
Send the word, send the word, over there,
That the Yanks are coming, the Yanks are coming,
The drums rum-tumming ev'rywhere.
So prepare, say a pray'r,
Send the word, send the word to beware.
We'll be over, we're comin' over,
And we won't be back till it's over, over there.

2. Johnny get your gun, get your gun, get your gun.
Johnny, show the Hun you're a son of a gun.
Hoist the flag and let her fly,
Yankee Doodle do or die!
Pack your little kit, show your grit, do your bit.
Yankees, to the ranks from the towns and the tanks!
Make your mother proud of you
And the old Red White and Blue.

[The Levy collection has another copy of the sheet music that has French lyrics as well as English. I didn't try to transcribe that one because I don't think my French fluency would be up to the task. It also has a cover illustration by Norman Rockwell.]