The title is a lyrical reference to Bob Dylan's song "," which contains the line, "There's an arrow on the doorpost / Saying this land is condemned."
It suggests that despite the attempts at a peace treaty, the conflict is already past the point of no return. [S3E13] Arrow on the Doorpost
Fans have also linked it to the Native American tradition of placing a hatchet or arrow in a post to signal that war is coming. Key Plot Points The title is a lyrical reference to Bob