Don't give credit to Eugene Debs. "Rich man's war, poor man's fight!" was a rallying cry during the New York City draft riots of 1863, when it was actually true: the wealthy could avoid the draft by paying a bounty. In the Confederacy, men who owned 20 or more slaves were exempt from service.
I have never heard that it was first used in the Civil War.Please cite your source. Debs definitely did say it "In 1918 Debs gave a speech, which resulted in him going to prison, during which he said, And here let me emphasize the fact -- and it cannot be repeated too often -- that the working class who fight all the battles, the working class who make the supreme sacrifices, the working class who freely shed their blood and furnish the corpses, have never yet had a voice in either declaring war or making peace. It is the ruling class that invariably does both. They alone declare war and they alone make peace. They themselves did not go to war anymore than the modern feudal lords, the barons of Wall Street go to war
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