Schlieffen Plan
When Schlieffen retired in 1906, and the WW1 came up 9 years later, in August 1914, the German officers and tactic leaders dug up the plan that Schlieffen had made and thought that the plan would work like it would in Schlieffen's hypothetical war. However, the plan didn't work, because the plan was outdated and things had changed a lot within the decade.