Which treaty ended World War I with Germany?

Versailles, signed in June 1919 in the Hall of Mirrors - the room in which the German Empire had been proclaimed in 1871, chosen deliberately, which is the sort of symbolism that does long-term damage. Germany was not permitted to negotiate; the terms were presented and signature demanded.

Article 231, the war guilt clause, was the one that mattered politically. It assigned responsibility for all loss and damage to Germany and its allies, and was the legal basis for reparations - and it became the single most effective grievance in German politics for the next twenty years. The economist John Maynard Keynes resigned from the British delegation and wrote a furious book arguing that a settlement designed to impoverish a defeated economy would destabilise Europe.

Whether it caused the next war is a genuine historical argument rather than a settled point. The reparations were substantially reduced and then largely unpaid; some historians argue the treaty was too harsh to conciliate and too soft to cripple, which is the worst of both; others that Germany's economic troubles owed far more to the Depression, and that blaming Versailles was politically useful rather than accurate. The final instalment of the associated debt was paid by Germany in 2010.