All your strength is in your union; all your danger is in discord.
(Henry Wadsworth Longfellow, "The Peace Pipe")
The source for the proverb is Forty Thousand Quotations: Prose and Poetical by Charles Noel Douglas (Bartleby.com). The poster is made with AutoMotivator. The image shows a "Happy While United" coin struck by the State of Virginia in 1780 depicting a Virginia colonial smoking a peace pipe with a member of the Cherokee nation; I found the image at Wikipedia.