Here's one that usually get people going. The tune is familiar to them and a peace crowd will appreciate the humor.

      - Mark

Universal Military Training

(to the melody of "Johnny Comes Marching Home")

For you and me all war must cease, hurrah, hurrah,
We have the perfect formula for peace, hurrah,
Oh I'll shoot you and you'll shoot me,
and then how happy we will be,
Universal military training.

Oh we will drop an atom bomb upon the Russ',
And they will drop an atom bomb on us, hurrah,
And then we're sure to have peace allright,
Cause there'll be nobody left to fight,
Universal military training.

When life upon this earth is gone, hurrah, hurrah,
Then up in heaven we'll carry on, hurrah, hurrah,
We'll give them guns and they'll be proud,
As they go marching cloud to cloud,
Universal military training.